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. (1.4, 2.2) and (4.1, 2.4)
b. (3, 9) and (8, 9)
c. (1 1/4, 2) and (1 1/4, 8)