Final answer:
The legitimacy of the CPC is questioned due to the lack of accountability mechanisms in a single-party system, similar to challenges that can arise in a two-party system where smaller parties are deemed non-viable.
Step-by-step explanation:
Arguments against the legitimacy of a particular political entity like the CPC (Communist Party of China) generally involve governance issues such as the lack of mechanisms for accountability. In a system where a single party holds power, critics argue that it becomes challenging for citizens to hold their leaders accountable due to the absence of competitive elections and a free press. Moreover, in a two-party system, which is common in some democracies, the system perpetuates itself because voters often feel that casting their votes for smaller parties is a wasted effort, as these parties are not viewed as viable. This phenomenon can discourage the emergence of alternative political voices and entrench the power of the two major parties, potentially leading to similar challenges of accountability as seen in a single-party state.