On the Issue of a President's Right to Impound Funds

On the issue of a president's right to impound funds, the U.S. Constitution says

A) that a president must spend the money that Congress appropriates.
B) that a president does not have to spend money that Congress appropriates.
C) that a president may spend money that Congress does not appropriate.
D) that a president may spend money that Congress does not appropriate if congressional leaders support such expenditures.
E) nothing.