(Consider This) If the Law of Diminishing Returns Applies to Study

(Consider This) If the law of diminishing returns applies to study time,

A) the tenth hour of study will likely be less productive than the third.
B) this implies that longer lectures are less productive than shorter ones.
C) there is no benefit to studying a subject more than five hours in any given day.
D) people with less intelligence necessarily experience diminishing returns sooner than those with greater intelligence.