Final answer:
The specific region of an enzyme responsible for catalysis is called the active site. It is a small region where the substrate binds, allowing the reaction to occur. Therefore, the correct option is b) Active site.
Step-by-step explanation:
The specific region of an enzyme responsible for catalysis is called the active site. It is a small region within the enzyme where the substrate binds for the reaction to occur. The active site has a unique shape that only allows a specific substrate to bind, similar to puzzle pieces fitting together. Once the enzyme/substrate complex is formed, the reaction occurs, and the product is released from the active site.