An irregular mode of reproduction in which an embryo develops without fertilisation is described by which of the following terms: 1. Parthenogenesis 2. Apogamy 3. Sporophytic budding. Select the correct combination using the code given below.

Introduction / Context:
Reproduction without fertilisation, where an embryo arises from an unfertilised egg or other cell, is an important concept in both zoology and botany. These processes are considered irregular or special modes of reproduction and are given specific names such as parthenogenesis and apogamy. Some plant species also show sporophytic budding, another way of forming a new sporophyte without the usual sexual fusion. This question asks you to identify which of the listed terms describe development of an embryo without fertilisation and to choose the correct combination of statements.

Given Data / Assumptions:
• The definition given is an irregular mode of reproduction resulting in the development of an embryo without fertilisation.• Three terms are listed: 1. Parthenogenesis 2. Apogamy 3. Sporophytic budding.• The options provide different combinations of these three statements.• We assume standard textbook meanings of each reproductive term in the context of plants and animals.

Concept / Approach:
Parthenogenesis refers to development of an embryo from an unfertilised egg cell, common in some invertebrates and a few vertebrates and also observed in some plants. Apogamy in plants describes the formation of a sporophyte from a gametophyte without the fusion of gametes, meaning a new sporophyte embryo arises without fertilisation. Sporophytic budding can refer to situations where sporophytic tissue buds off to form a new sporophyte, again bypassing the usual fertilisation event. In all three, the key idea is that an embryo or new sporophyte develops without gametic fusion. Therefore all three terms satisfy the definition and should be included in the correct combination.

Step-by-Step Solution:
Step 1: Consider parthenogenesis. It is defined as development of an individual from an unfertilised egg, clearly fitting the phrase embryo without fertilisation.Step 2: Consider apogamy. In ferns and some other plants, apogamy involves a sporophyte arising from a gametophyte cell directly without fusion of male and female gametes. This again fits the idea of embryo formation without fertilisation.Step 3: Consider sporophytic budding. Here, new sporophytic structures or embryos bud off from existing sporophytic tissue without a fertilisation event. This is also a form of asexual or irregular reproduction leading to embryo development without gametic fusion.Step 4: Since all three processes produce an embryo or new sporophyte without fertilisation, all of the statements 1, 2, and 3 fulfill the definition.Step 5: Select the option that includes 1, 2 and 3 together.

Verification / Alternative check:
You can verify by recalling examples from standard botany and zoology texts. Parthenogenesis is classically illustrated by aphids, honey bees, and some lizards, where unfertilised eggs develop into new individuals. Apogamy is illustrated by certain ferns where the sporophyte arises directly from the gametophyte without fertilisation. Sporophytic budding is described as a vegetative, asexual formation of new sporophyte structures. In each case, fertilisation is bypassed, confirming that all three terms fall under the broad definition given in the question stem.

Why Other Options Are Wrong:
The options 1 only and 2 only wrongly exclude other valid examples that also match the definition. The option 1 and 2 only ignores sporophytic budding, which is another recognised mode of reproduction without fertilisation. The option 3 only ignores the widely accepted phenomena of parthenogenesis and apogamy. Since the definition in the stem is broad and encompasses embryo formation without any fertilisation, it applies to all three processes rather than a restricted subset.

Common Pitfalls:
Students often remember parthenogenesis well but are less confident about the precise meanings of apogamy and sporophytic budding. This can lead them to choose a partial answer such as 1 only or 1 and 2 only. Another pitfall is to assume that apogamy always requires some form of hidden fertilisation, which is not the case. To avoid these mistakes, focus on the key phrase embryo without fertilisation and test whether each listed term describes a reproductive pathway that bypasses gametic fusion. When applied consistently, this reasoning shows that all three processes fit the definition.

Final Answer:
The irregular modes of reproduction described in the question are 1, 2 and 3, that is, parthenogenesis, apogamy, and sporophytic budding all involve embryo development without fertilisation.