Assertion (A): Many desert plants such as cactus have their leaves in the form of spines.
Reason (R): Spines reduce the loss of water from the plant through transpiration.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Both Assertion (A) and Reason (R) are correct, and R is the correct explanation of A.
In an Assertion-Reason question, each statement is checked for truth first, and then R is tested as the cause of what A describes.
Assertion — correct. In plants like cactus the leaves are absent, very small or changed into spines.
Reason — correct. Plants lose water through their leaves by transpiration; thin spines have very little surface, so much less water is lost.
Water is scarce in the desert, and having spines in place of broad leaves is an adaptation to save water, so R explains A.