Correct Option (3)
The passage explicitly states that the "ideological bias" is characterized by "the assumptions that an unregulated market is fair and competent." Therefore, option (3) accurately reflects this specific assumption attributed to the apologists of the system within the context of their ideological bias.
Incorrect Options:
Options (1) and (2) are incorrect because they misrepresent the nature of the assumption. The passage links the ideological bias to the belief that an unregulated market is both fair and competent. Separating these qualities or negating one of them, as in "fair but not competent" or "not fair but competent," distorts the passage's description of the bias.
Option (4) is incorrect as it directly contradicts the passage. The text clearly identifies an "ideological bias" and specifies its content. Stating that the free market is "neither fair nor biased" denies the existence of the bias explicitly mentioned and defined in the passage.