Final answer:
Insects have a three-part digestive system which consists of a mouth, a crop, and a gizzard, not including the trachea, as it is part of the respiratory system. Option 2 is the correct answer.
Step-by-step explanation:
The three-part digestive system of insects includes the following components: a mouth, a crop, and a gizzard. Therefore, the correct answer to the question is option 2) Mouth, crop, and gizzard. Insects have a well-developed digestive system, which begins with the mouth where food is ingested. The food then moves to the crop, where it is stored and sometimes preliminary digestion occurs.
Finally, the gizzard grinds the food, aided by particles or grit that the insect may have ingested. It is important to note that insects do not have a trachea as part of their digestive system; the trachea is actually part of their respiratory system, with spiracles being the openings for air to enter. The insect's digestive system is efficient and specialized, reflecting the creature's unique dietary requirements and feeding strategies.