Which Structural and Functional Feature(s) Listed Are Key to an Enzyme's

Which structural and functional feature(s) listed are key to an enzyme's activity?

A) contains an active site where the enzyme can interact with a specific substrate
B) consumed each time a reaction takes place
C) consumed each time a reaction takes place and contains an active site where the enzyme can interact with a specific substrate
D) consumed each time a reaction takes place and consists of a three- dimensional protein structure that interacts with a substrate in a fixed "lock- and- key" model
E) consists of a three- dimensional protein structure that interacts with a substrate in a fixed "lock- and- key" model