Which one of the following shows a unique relationship with an insect that has coevolved with it and that is the only insect that can pollinate this tree?

Fig (genus Ficus) shows an obligate mutualism with fig wasps (family Agaonidae), a classic example of coevolution. Each species of fig is typically pollinated by its own specific species of fig wasp, and the wasp can only reproduce inside the fig's specialized inflorescence (syconium). Neither the fig nor the wasp can complete its life cycle without the other. Mahua, sandalwood, and silk cotton are pollinated by various insects, bats, or birds and do not show such unique one-to-one obligate pollination relationships.