Question

HELP PLEASE):
Hi I really don't understand these, and I keep on not passing my quiz, I need help ASAP!

Determine whether the subordinate clause in the sentence below is an adjective clause, an adverb clause or a noun clause.

A letter that is mailed today will be delivered by 10:30 A.M. tomorrow.
a.
noun clause
b.
adjective clause
c.
adverb clause

The president is carefully guarded wherever he goes.
a.
noun clause
b.
adjective clause
c.
adverb clause

My uncle is the one who bought me a puppy for my birthday.

a.
noun clause
b.
adjective clause
c.
adverb clause