posted by CARNITA .
The Senate has the sole power to
a. declare war.
b.approve major presidential appointments.
c.regulate the District of Columbia.
d.issue patents and copyrights.
e. establish post offices and post roads.
I think it is b.
Since this is not my area of expertise, I searched Google under the key words "powers of US senate" to get these possible sources:
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.