I'm sorry the house is not available any longer. It ______ to a timber tycoon.

Correct answer: has been sold — present perfect passive.

Why this is correct:

• The present perfect passive (has/have + been + past participle) shows a past action with a present result. "Has been sold" indicates the sale happened at an unspecified time and explains why the house is not available now.

• Formation reminder: has/have + been + past participle (use "has" for third-person singular).

Why the other choices are wrong:

• "was being sold" describes an action in progress in the past (past continuous passive), not a completed action that results in the house being unavailable now.

• "will be sold" is future tense and suggests the sale will happen later, which contradicts the statement that the house is already not available.

• "is sold" (simple present passive) is used for general truths or habitual events and sounds unnatural for a recent completed sale that has present consequences.

Short tip: Use the present perfect passive to report that something was done at an unspecified time in the past when its result is relevant now. Avoid past-simple time expressions (yesterday, a week ago) with the present perfect.