Explanation:

- Option 1: was reading

- Suggests an action that was ongoing.

- Implies he was in the process of reading at some point in the past.

- Option 2: has been reading

- Indicates an action that started in the past and focuses on the present relevance.

- Not suitable if the action was completed in the past.

- Option 3: had read

- Used for actions completed before another past action.

- Implies the reading was completed before another event.

- Option 4: read

- This is the past simple tense.

- Fits when describing a completed action in the past.

- ? Based on the structure, this is the correct choice for a simple past action.