Which out of the following is a substrate-specific enzyme?

Q. Which out of the following is a substrate-specific enzyme?
A. Hexokinase
B. Thiokinase
C. Lactase
D. Decarboxylase
Answer: Lactase

A. Hexokinase
B. Thiokinase
C. Lactase
D. Decarboxylase
Answer: Lactase