The correct option is: object.

To understand why ‘lemons’ is the object of the sentence, we can break down the sentence structure step-by-step:
1. Subject: The subject is the person or thing performing the action. In this sentence, ‘The shopkeeper’ is doing the action, so ‘The shopkeeper’ is the subject.
2. Verb: The verb is the action word in the sentence. Here, ‘sells’ is the action being performed, so it is the verb.
3. Object: The object (specifically, the direct object) is the noun or pronoun that receives the action of the verb. We can identify the direct object by asking ‘what’ or ‘whom’ after the verb: ‘The shopkeeper sells [what?]’
The answer is ‘lemons’. Therefore, ‘lemons’ is the object of the sentence because it is the entity receiving the action of being sold.