In biochemistry, which statement best defines an enzyme?

• A. A non-specific solvent that accelerates all reactions equally by increasing temperature
• B. A molecule that increases reaction rate by raising the activation energy to favor product formation
• C. A biological catalyst, usually a protein (or sometimes RNA), that increases the rate of a specific chemical reaction by lowering the activation energy without being consumed
• D. A reactant that is permanently used up during a reaction and must be replenished after each catalytic cycle

Answer: (C)