The damaging stage of white grub is

Understanding White Grub Damage
Let's break down why the correct answer is (C) Larva.

White Grubs: The Basics
White grubs are the larvae of scarab beetles.
Think of a beetle's life cycle: egg -> larva -> pupa -> adult.

Why Larva is the Damaging Stage
The larval stage (grub) is when they live in the soil and feed on plant roots.
This feeding is what causes the significant damage to crops and lawns.

Why Other Options Are Incorrect
* Option A: Nymph and adult: Insects do not have nymph stage.
* Option B: Grub and adult: While adults might feed a little, their feeding is minimal compared to the grubs.
The grub stage is the primary damaging stage.
* Option D: Only adult: The adults of some scarab beetles may cause minor damage by feeding on foliage.
The real problem is the grubs feeding on roots.

Therefore, the answer is (C) Larva because the larva (grub) is the stage that causes the most significant damage by feeding on plant roots.