Correct answer: (a) Both (A) and (R) are true and (R) is the correct explanation of (A)
Explanation
- A
Both (A) and (R) are true and (R) is the correct explanation of (A)
(a) Both true and (R) explains (A). Tropical countries hold the most butterfly species, and the keyed reason is their poor tolerance of low temperature, which confines diversity to warm, humid belts. (a) Official key.
- B
Both (A) and (R) are true but (R) is not the correct explanation of (A)
(b) Both true but (R) does not explain (A). The stored key treats cold intolerance as the explanation, not a coincidence.
- C
(A) is true but (R) is false
(c) (A) true, (R) false. Low-temperature intolerance is not treated as false here; alpine exceptions do not overturn the key.
- D
(A) is false but (R) is true
(d) (A) false, (R) true. Tropical richness of butterflies is not denied.
Summary. Official key is (a). Assertion and Reason both stand, and inability to thrive in the cold is the explanation given for peak butterfly species richness in the tropics.