Explanation:

- Option 1: has gone

- Incorrect. "Has gone" is present perfect tense. It suggests an action that happened at an unspecified time or relevance to the present. "Last week" requires simple past.

- Option 2: gone

- Incorrect. "Gone" alone cannot be used as a verb. It needs a supporting verb like "has" to be correct. Otherwise, it is not a complete action.

- Option 3: go

- Incorrect. "Go" is present tense and does not fit with "last week," which indicates a past action.

- Option 4: went

- Correct. "Went" is simple past tense and is the appropriate choice to indicate an action completed in the past.