From Article I, Section 2:
The House of Representatives shall chuse their Speaker and other Officers; and shall have the sole Power of Impeachment.
From Article I, Section 3:
The Vice President of the United States shall be President of the Senate, but shall have no Vote, unless they be equally divided.
The Senate shall have the sole Power to try all Impeachments. When sitting for that Purpose, they shall be on Oath or Affirmation. When the President of the United States is tried, the Chief Justice shall preside: And no Person shall be convicted without the Concurrence of two thirds of the Members present.
Suppose that the House of Representatives impeaches the Vice President. Who presides over the Senate during the trial?
Remember, you must justify your answer using only what's in the Constitution.