The theory of consumer behavior assumes that

A) consumers behave rationally, attempting to maximize their satisfaction.
B) consumers have unlimited money incomes.
C) consumers do not know how much marginal utility they obtain from successive units of various products.
D) marginal utility is constant.

The theory of consumer behavior is based on the assumption that consumers act rationally, seeking to maximize their utility or satisfaction from the goods and services they purchase. This involves making decisions on what to buy based on the utility those goods or services provide relative to their cost, rather than having unlimited incomes, being unaware of the marginal utility obtained, or marginal utility remaining constant.