This author has perspicuity in his style.

Answer: Option C

Perspicuity : something that can be seen through.
Frankness : the quality of being open, honest, and direct in speech or writing.
Bluntness : the quality of being direct and outspoken.
Obtuseness : not clear.
Vivacity : (especially in a woman) the quality of being attractively lively and animated.

Antonym of Perspicuity is Obtuseness