Red Data Book deals with
Organism on the verge of extinction
The correct option is A.
Explanation of correct option:
Explanation of incorrect options:
Option B
Endemic plants are those plants found in particular geographical regions.
Option C
Photoperiodism is a physiological response of plants and animals to the length of day and night.
Option D
Extinct species that have stopped breeding and no longer exist.
Final answer: Red Data Book deals with organisms on the verge of extinction.