Consider the function f which is defined by the following graph, where the points c1 and c2 are on the -axis. (Some of you may not be able to view the horizontal line.) C2 C1 OWhich of the following MUST be TRUE? (1) f is continuous at C1. (Il) f is discontinuous at c2. O a. (1) Only O b. (11) Only O c. All of them O d. None of them