30 They're tired. They ..... all day.

Analysis:

The sentence states that they are tired, and the reason is that they have been engaged in an activity all day. The present perfect continuous tense ('have been gardening') is used to describe an action that started in the past, continued for a duration, and has a result in the present (tiredness).

Breakdown:

• A garden: Incorrect. This is the base form of the verb.
• B gardened: Incorrect. Past simple, suggests a completed action in the past, not necessarily ongoing up to the point of being tired.
• C have been gardening: Correct. Present perfect continuous, indicating an action that has been happening over a period and explains the current state of tiredness.

Translated Question:

30 Они устали. Они ..... весь день.