For each pair of points below, think about the line that joins them. For which pairs is the line parallel to the x-axis? Circle your answer(s). Without plotting them, explain how you know.
a. (3.2, 7) and (5, 7)
b. (8, 8.4) and (8, 8.8)
c. (6 1/2, 12) and (6.2, 11)