If the uncatalyzed reaction occurs in a single elementary step, why is it a slow reaction?

The choices can be found elsewhere and as follows:

A)The reaction requires the collision of three particles with the correct energy and orientation. 
B) All reactions that occur in one step are slow. 
C)The probability of an effective three-particle collision is low. 
D) The transition state is low in energy.

I think the correct answer from the choices listed above is option C. If the uncatalyzed reaction occurs in a single elementary step, it is a slow reaction because the probability of an effective three-particle collision is low.