The answer is D. Nymph.
A larva is a young insect that undergoes complete metamorphosis. It is typically different in form from the adult insect and has a different diet. The larva grows and molts several times before pupating.
A pupa is the stage in an insect’s life cycle between the larva and the adult. It is typically a non-feeding stage during which the insect undergoes metamorphosis.
A caterpillar is the larval stage of a butterfly or moth. It is typically a worm-like creature with a soft body and many legs.
A nymph is the immature form of an insect that undergoes incomplete metamorphosis. It is typically similar in form to the adult insect, but smaller and with fewer wings.
In conclusion, the answer is D. Nymph because it is the only option that does not describe an insect that undergoes complete metamorphosis.