Which one of the following is an example of co-evolution?

The correct answer is Option (3) → Wasp and Fig

Option (3) Wasp and Fig — Correct. Each fig species is pollinated only by its partner wasp, and the wasp lays eggs in the fig.

NCERT Extract:
Population Interactions – “… In many species of fig trees, there is a tight one-to-one relationship with the pollinator species of wasp (Figure 11.4). It means that a given fig species can be pollinated only by its ‘partner’ wasp species and no other species. The female wasp uses the fruit not only as an oviposition (egg-laying) site but uses the developing seeds within the fruit for nourishing its larvae. The wasp pollinates the fig inflorescence while searching for suitable egg-laying sites.”