What is the primary difference between a discrete-time Markov Chain (DTMC) and a continuous-time Markov Chain (CTMC)?

a) DTMC has time-dependent probabilities, while CTMC does not

b) CTMC allows transitions at any point in time, while DTMC transitions at fixed intervals

c) DTMC is deterministic, while CTMC is random

d) CTMC has a finite state space, while DTMC does not