Biochemistry The following vitamin acts as a cofactor for glycogen phosphorylase: A Thiamine pyrophosphate (B1) B Riboflavin (B2) C Pyridoxal phosphate (B6) D Methyl cobalamin (B12) 💡 Explanation The following vitamin acts as a cofactor for glycogen phosphorylase: ✓ Correct Answer: C. Pyridoxal phosphate (B6)