The correct answer is: egg-nymph-adult.
Locusts undergo incomplete metamorphosis, which means that they do not have a pupal stage. Instead, they go through three stages: egg, nymph, and adult.
The life cycle of a locust begins when a female locust lays her eggs in soil. After a period of incubation, the eggs hatch into nymphs, which look like small versions of adult locusts but lack wings. Nymphs go through several molts as they grow and develop, becoming larger and more mature with each molt. Eventually, they reach adulthood and develop wings that enable them to fly and migrate long distances in search of food and suitable breeding sites.
The adult stage is the final stage of the locust life cycle, during which time the insects mate, lay eggs, and die. Depending on environmental conditions, the entire life cycle of a locust can take anywhere from several weeks to several months.