Which of the following can be true? If an answer is false, state why it is false

Question:

Which of the following can be true? If an answer is false, state why it is false
a. The graph of fx(x) can have jumps (i.e., can be discontinuous).
b. The graph of Fx(x) for discrete random variables can have jumps.
c. The graph of Fx(x) for continuous random variables can have jumps.
d. The graph of px(x) can have jumps.