What do Muslims believe that the Sharia describes?

A. the basis for secular law in Muslim nations
B. the rules for proper conduct by Muslims
C. the words and actions of Muhammad
D. the word of god revealed to Muhammad

The correct answer to this is "the rules for proper conduct by Muslims". I put the other answer and got it wrong and it showed this as the correct answer. Hope this helps!

D. the word of god revealed to Muhammad