Answer:
p=4 and q could be any real number (except 1 because then CD would not be a line since the points would lie on top of each other).
Step-by-step explanation:
For CD to be horizontal, both of the y coordinates for CD need to be equal. Since we are already given one of the y coordinates (the y coordinate for D is 4), then we know that the y coordinate for C (p) is 4 as well). Since it doesn't really matter what q is (any value of q except 1 would create a horizontal line with point C as long as p=4), it is any real number except 1.
