China, with most decision-making power concentrated into a few members of the communist party is best described as a

China, with most decision-making power concentrated into a few members of the communist party is best described as an autocracy.

Explanation:

Autocracy is a form of government in which there is a single holder of state-political power, that is, power is concentrated in a single ruler, which may be a leader, a committee, a party, an assembly, etc. The ruler has absolute control at all levels of the state. The term autocracy has functionality only to describe the concentration or distribution of state power control, and is not meant to assess the presence or absence of democratic legitimacy of a government. There is indeed the possibility of an autocratic government coming to power via democratic elections and even holding elections periodically.