Which of the following statements is true?

a$)$ Only one of the three condition code registers of the LC$-3$ can be set to TRUE at a time.

b$)$ The value of only one of the three condition code registers of the LC$-3$ can change at a time.

c$)$ Multiple of the three condition code registers of the LC$-3$ can be set to TRUE at a time.

d$)$ The three condition code registers of the LC$-3$ are mutually exclusive and can change values independently of the others.