Apart from the Article II: B, C, and D are not duties of the president.
B: no, this would be a waste of time, and anyway, this is the role of the parliament, i.e. the legislative Branch, and the president is the executive branch
C: no, this belongs to the judicial branch of the government
d: this depends on what the interpretation is for, but it's not a role of the president anyway.
The correct answer is A: the president is the head of the executive Branch of the Government, which carries the laws th were passed.
Now, I am not too sure which part of the Article II is relevant, but the beginning is probably already relevant for A: "The executive power shall be vested in a President of the United States of America."
