To Ensure a Well-Defined Solution to the Consumers' Intertemporal Choice

To ensure a well-defined solution to the consumers' intertemporal choice problems, we must assume that consumers' preferences exhibit the properties that

A) the consumer likes diversity and that more is sometimes preferred to less.
B) they are all identical and that more is always preferred to less.
C) more is sometimes preferred to less and that first-period consumption and second-period consumption are both normal goods.
D) more is sometimes preferred to less and that first-period consumption and second-period consumption are both inferior goods.
E) more is preferred to less and that the consumer prefers diversity.