A Surprise from the Pioneer Venus Photos Was That

A surprise from the Pioneer Venus photos was that:

A) the craters on Venus are all large.
B) the clouds rotate around the planet in only four days, very unlike the slow surface rotation.
C) the clouds of Venus are mainly water vapor, like our own.
D) the highest volcano, Maxwell Mons, protrudes above the cloud deck.
E) no impact craters at all are found on the Venusian surface.