How does the co-evolution of plant-animal mutualists benefit their mu…

The correct answer is Option (4) → All of the above

In plant-animal mutualism, plants offer rewards (pollen, nectar, fruits) to animals that pollinate their flowers or disperse their seeds. The evolution of the flower and of its pollinator are tightly linked; this is co-evolution. The fig and its wasp are the book’s example.

Option (1) To safeguard the mutually beneficial system against cheaters — Correct statement, but it is only one of the correct points, so on its own it is not the answer. The mutually beneficial system must be safeguarded against ‘cheaters’, such as animals that steal nectar without pollinating. Co-evolution keeps the partners tightly linked for this reason.

Option (2) To ensure that a specific plant species can only be pollinated by its partner animal species and no other species — Correct statement, but it is only one of the correct points, so on its own it is not the answer. In many fig species there is a one-to-one relationship with the pollinator wasp, so a fig species is pollinated only by its ‘partner’ wasp species and no other.

Option (3) To allow the animal to utilise the plant for both oviposition and pollination — Correct statement, but it is only one of the correct points, so on its own it is not the answer. The female wasp lays its eggs in the fig fruit and feeds its larvae on the developing seeds. While searching for egg-laying sites it pollinates the fig inflorescence.

NCERT Extract:
Population Interactions – “… But the mutually beneficial system should also be safeguarded against ‘cheaters’, for example, animals that try to steal nectar without aiding in pollination. Now you can see why plant-animal interactions often involve co-evolution of the mutualists, that is, the evolutions of the flower and its pollinator species are tightly linked with one another. 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.”