In botany, plants that flower and set seeds only once in their lifetime and then die are called:

Introduction / Context:
This question comes from plant biology and terminology. It focuses on the special category of plants that flower only once in their lifetime, produce seeds, and then die. Understanding this term helps you classify plant life cycles and distinguish between plants that reproduce once and those that flower repeatedly over many seasons. The question also checks whether you can separate similar sounding biological terms used in different contexts.

Given Data / Assumptions:

• The central idea is plants that flower only once in their lifetime and then die.
• Options include monocots, monocarpic, monogenic, and monogamous.
• Basic botanical vocabulary and life cycle concepts are assumed.

Concept / Approach:
Monocarpic plants are those that flower only once during their life cycle, produce fruits and seeds, and then die. Examples include many annuals (such as wheat and rice) and some long lived species like certain bamboos and Agave, which may live for years in vegetative form but flower only once. The prefix mono means one, and carp refers to fruit, indicating a single fruiting period. Monocots, by contrast, are a large group of flowering plants characterised by having a single cotyledon (seed leaf) and other features, but they may flower multiple times. Monogenic refers to traits controlled by a single gene, and monogamous refers to mating systems in animals or humans, not plant flowering frequency. Therefore, the correct term for plants that flower once and die is monocarpic.

Step-by-Step Solution:

Verification / Alternative check:
Botany textbooks describe three broad types of plant life cycles: annuals, biennials, and perennials. Within these categories, they note that monocarpic plants (also called semelparous in ecology) reproduce only once and then die, while polycarpic (iteroparous) plants can flower and set seeds multiple times over many seasons. Examples such as bamboo flowering after many years and then dying are often cited as striking cases of monocarpic life histories. These sources clearly associate the term monocarpic with the one time flowering and death pattern, confirming that option B is correct.

Why Other Options Are Wrong:

Monocots, plants with a single cotyledon in the seed, is wrong because monocots can be annuals or perennials and may flower many times; the term refers to seed structure, not flowering frequency.

Monogenic, traits controlled by a single gene, is incorrect because it belongs to genetics, describing how traits are inherited rather than plant life cycle patterns.

Monogamous, organisms that pair with only one mate at a time, is wrong because it refers to mating systems in animals and sometimes humans, not to how often plants flower.

Common Pitfalls:
Students often focus on the mono prefix and guess without considering the full word. This leads to confusion between monocot and monocarpic or between biological terms used in different subfields. To avoid such mistakes, pay attention to the root words: carp refers to fruit, so monocarpic literally suggests a single fruiting, which matches the definition. Remember that monocarpic plants flower once, set seeds, and then die, which is exactly what the question describes.