In environmental biology, the Red Data Book primarily contains information about which of the following groups?

Introduction / Context:
The Red Data Book is an important resource in environmental science and conservation biology. It is closely linked with efforts to protect biodiversity by documenting species that are at risk of extinction. This question asks the learner to identify what kind of species information the Red Data Book primarily contains. Knowing this helps in understanding global conservation strategies and the role of organisations like the International Union for Conservation of Nature (IUCN).

Given Data / Assumptions:

• The focus is on the Red Data Book as a conservation document.
• The options range from all plants and animals to endangered or extinct species.
• We assume the standard examination level definition used in textbooks and environment sections.

Concept / Approach:
The Red Data Book, often associated with the IUCN Red List and national red lists, is a compilation of information on the conservation status of species. The key concept is that it lists species that are under various categories of threat, such as vulnerable, endangered, critically endangered, or near threatened. While extinct species may also be mentioned, the main purpose is to record species that are at risk and need conservation attention. Thus the correct approach is to identify the option that captures the idea of endangered or threatened species rather than all species in general.

Step-by-Step Solution:
Step 1: Option A, all plant species, is too broad. The Red Data Book does not attempt to list every plant on Earth, only those with specific conservation concern. Step 2: Option B, all animal species, is also too broad and inaccurate, because the document focuses on conservation status rather than listing every animal species. Step 3: Option C states all endangered species, which matches the central idea that the Red Data Book records species that are endangered or otherwise threatened. Step 4: Option D, all extinct species, is incorrect, because extinct species are only one possible category and the main focus is on species that are still existing but in danger. Step 5: Therefore, the best description is that the Red Data Book contains data on endangered species.

Verification / Alternative check:
Environment and biology textbooks often define the Red Data Book as a catalogue of species facing a high risk of extinction, frequently using the phrase endangered and threatened species. Some national and international versions list categories such as critically endangered, endangered, vulnerable, and so on. While information on extinct species can appear, the core purpose is to highlight species under threat. This confirms that the correct interpretation is linked to endangered species, not all plants, all animals, or only extinct organisms.

Why Other Options Are Wrong:

• All plant species: This would be an impossibly large list and does not reflect the conservation focus of the Red Data Book.
• All animal species: Again too broad and unrelated to the key idea of extinction risk.
• All extinct species: Extinct species may be mentioned, but the primary concern is to document and protect species that are still alive but endangered.

Common Pitfalls:
Some learners mix up the Red Data Book with general taxonomic catalogues or encyclopedias, which list all species. Others focus too narrowly on the word red and assume it means species already lost. To avoid this, remember that the Red Data Book is a warning list for species that are in danger and need conservation. The colour red symbolises danger, alerting policymakers and the public to the urgency of protecting these species.

Final Answer:
The Red Data Book primarily contains data about all endangered species and their conservation status.