A
Fig
B
Mahua
C
Sandalwood
D
Silk cotton
Correct answer: (a) Fig
Explanation
- A
Fig
Fig. Each fig species is pollinated by its own fig wasp — a classic obligate mutualism.
- B
Mahua
Mahua. Bat- and insect-pollinated, not a single coevolved insect.
- C
Sandalwood
Sandalwood. Not an obligate one-insect tree in this sense.
- D
Silk cotton
Silk cotton. Bird- and bat-pollinated kapok/semal, not a unique wasp.
Summary. Official key is (a) fig. Ficus and agaonid fig wasps are the textbook coevolved pair: the wasp is the only pollinator of that fig, and the fig is the only host of that wasp. Mahua, sandalwood and silk cotton do not have that exclusive insect lock.