Final answer:
The Manchester class of digital encoding schemes solves the synchronization problem by ensuring that each bit has some type of signal change.
Step-by-step explanation:
The answer to the question is a. Manchester.
The Manchester class of digital encoding schemes solves the synchronization problem by ensuring that each bit has some type of signal change. In Manchester encoding, the data is represented by the transition in the middle of each bit. A high-to-low transition represents a 0, while a low-to-high transition represents a 1.
NRZ encoding, on the other hand, does not ensure that each bit has a signal change. In NRZ encoding, a high voltage level represents a 1, while a low voltage level represents a 0.
Therefore, the correct answer is Manchester, option a.