Answer:
A.) the president's power to make treaties with foreign nations
Step-by-step explanation:
The Senate are regarded as the upper arm or section of the legislative, and saddled with responsibilities.
It should be noted and understood that the constitution gives the Senate the authority to approve treaties that is made by the executive branch. And this is done by voting. The treaties will be approved when two-thirds voted in favor.
Another important constitutional responsibility of the Senate is the confirmation of the president through majority vote.
In a nutshell, this means that when the treaties are not approved by the Senate, then they can not be engaged by the executive branch.