The correct answer is A. Necessary and proper
The necessary and proper clause, also called the elastic cause, is part of Article 1 of the United States Constitution. This clause essentially states that even though a power may not be explicitly given to the president, some powers can be assumed or implied. This clause is seen in US history in several instances including:
1) When Thomas Jefferson bought the Louisiana Purchase from France.
2) When George Washington created the First Bank of the United States.