Your answer is ∠7 and ∠8 are supplementary because they are a pair of adjacent angles that form a straight line.
We know that ∠7 and ∠8 are supplementary because they form a straight line, and straight lines have a total of 180 degrees.
Since the two angles are supplementary, we can eliminate the 2nd and 3rd choices.
∠7 and ∠8 are not corresponding angles, which leaves us with option 4.
Best of luck!
~collinjun0827, Junior Moderator