The correct answer is A) the Legislative branch.
The other options of the question were B) Judicial branch. C) President. D) Cabinet.
Impeachment at the Federal level is a legal process that is carried out by the Legislative branch.
In US politics, we understand as impeachment as the removal of an officer of the government from office. It is the Legislative branch that has the power to impeach an officer. It starts at the House of Representatives level and ends in the Senate, where Senators made the final vote. If you are interested in following this process, the Senate is about to start the impeachment of the actual President.