The correct options are
A They can acts as a catalyst
C They are active at normal body temperature
D They are the substances secreted in the body of an organism
Enzymes are the substances secreted in the body of an organism which bring about specific changes to chemical reactions. They acts as catalyst. A catalyst is a substance which speeds up a chemical reaction. Metabolic processes are impossible without enzymes. Enzymes are specific type of proteins and they are most active at normal body temperature.