Two Isoquants, Which Represent Different Output Levels but Are Derived

Multiple Choice

Two isoquants, which represent different output levels but are derived from the same production function, cannot cross because:

A) isoquants represent different utility levels.
B) this would violate a technical efficiency condition.
C) isoquants are downward sloping.
D) additional inputs will not be used by profit maximizing firms if those inputs decrease output.
E) Both B and D are true.