Answer:
The correct answer is option e) "a and c".
Explanation:
Single carbons are atoms needed for the biosynthesis of many molecules in cells, therefore the cells need a pathway to move group of atoms containing single carbons to make them available for the biosynthesis. S-adenosylmethionine and Tetrahydrofolate are two of the major carriers of single carbons in cells. S-adenosylmethionine (SAM) acts as a methyl (-CH3) donor and Tetrahydrofolate (THF) as a cofactor in enzymatic reactions.