Task: Question Answering
Input (English): Question: The hepatic synthesis of methionine from homocysteine ​​requires: 
 Options:  <1> Methylmalonyl-CoA mutase. <2> Methylcobalamin. <3> 5'-Adenosilcobalamin. <4> Coenzyme B6. <5> Methionine adenosyl transferase.
Output (English): 2