Concept:Insects with egg, nymph, and adult stages undergo incomplete metamorphosis.
Solution:Grasshoppers have three stages: egg, nymph, and adult.
Houseflies and mosquitoes have four stages: egg, larva, pupa, and adult.
Therefore, only the grasshopper shows egg, nymph, and adult stages.
Key point: Egg, nymph, adult = incomplete metamorphosis (grasshopper, cockroach). Egg, larva, pupa, adult = complete metamorphosis (housefly, mosquito, butterfly).
Answer:Option A (I only)