The purpose of a cofactor is to BLANK of catalysis. Coenzymes are a specific type of cofactor. They BLANK during the Krebs cycle, which is an important part in cellular metabolism. Option 1 choices:
A. blind an enzyme during the process

B. increase the rate

C. decrease the rate

D. prevent the formation

Option 2 choices:
A. blind tightly to proteins

B. bond with metallic ions

C. convert to inorganic substances

D. transport electrons