In the case of co-evolved plant pollinator mutualism where one of the species got extinct, what would be the impact on the other species?

It will get extinct

The correct answer is Option (3) → It will get extinct 

Co-extinctions: When a species becomes extinct, the plant and animal species associated with it in an obligatory way also become extinct. When a host fish species becomes extinct, its unique assemblage of parasites also meets the same fate. Another example is the case of a co-evolved plant-pollinator mutualism where extinction of one invariably leads to the extinction of the other.