Final answer:
The parts of the compound verb in the sentence are 'must depart,' 'fly,' 'identify,' and 'retrieve,' and the conjunction is 'and.' The correct answer is 'D) retrieve and and.'
Step-by-step explanation:
The compound verb in the sentence 'Each aircraft must depart from a small area, fly over a field, identify objects, and retrieve them' includes 'must depart,' 'fly,' 'identify,' and 'retrieve.'
These verbs are actions that the subject, which is 'each aircraft,' is supposed to perform. The conjunction used in the sentence is 'and', which connects the different verbs in the list of actions that the aircraft is expected to complete.
Therefore, the correct answer would be 'D) retrieve and and' since 'retrieve' is part of the compound verb, and 'and' is the conjunction used to join the listed actions in the sentence.