Suppose at a Price of $4 and at a Price

Suppose at a price of $4 and at a price of $6, John purchases 40 units of good X. Given this information, we know that

A) John's entire demand curve for good X is perfectly elastic.
B) John's entire demand curve for good X is inelastic.
C) John's demand for good X is perfectly inelastic between the prices of $4 and $6.
D) John's demand for good X is perfectly elastic between the prices of $4 and $6.
E) John's entire demand curve for good X is unit elastic.