The Reaction Rates of Many Spontaneous Reactions Are Actually Very $\Delta$

Multiple Choice

The reaction rates of many spontaneous reactions are actually very slow. Which of these statements is the best explanation for this observation

A) (K_p) for the reaction is less than one.
B) The activation energy of the reaction is large.
C) ( $\Delta$ G ^$\circ$ ) for the reaction is positive.
D) Such reactions are endothermic.
E) The entropy change is negative.