The Power of the President to Issue Executive Orders

The power of the president to issue executive orders:

A) is expressly provided for in the U.S. Constitution.
B) was granted to the president in an early Supreme Court decision.
C) is derived from express delegation from the legislative branch and is implied from the U.S. Constitution and state constitutions.
D) is subject to a two-thirds approval of the Senate.
E) exists only because it has never been challenged.