Answer:

Step-by-step explanation:
Hi there!
A)
B) 
C) 
D) 
We need to find which pairs are not equal.
We know that lines a and b are parallel. This means that line c is a transversal, and same with line d.
Let's start with A).
Are
and
equal?
Yes. This is true because when c is a transversal, angles 11 and 7 are alternate interior angles, meaning they're congruent, or equal. This is not the correct nswer choice as these angles are equal.
Are
and
equal?
Yes. When d is a transversal, angles 1 and 3 are called corresponding angles, which are always equal. Corresponding angles have 1 angle in between them.
Are
and
equal?
No. There is no reason that we can use to prove that
and
are equal. This means that C is the correct answer.
Are
and
equal?
Yes.
and
are called vertical angles. They share one vertice, or angle. Vertical angles are always congruent.
The correct answer is:

Hope this helps :)
Let me know if you have any questions!