Which of the following enzymes is responsible for the conversion of methemoglobin to normal hemoglobin?

A Methemoglobin reductase
B Cytochrome b5 reductase
C Diaphorase
D NADH methemoglobin reductase ✓

Explanation

NADH methemoglobin reductase is an enzyme that reduces methemoglobin to normal hemoglobin, using NADH as a cofactor.

Source

Biochemistry textbook by Stryer
Hematology Hematology: Hemoglobin and Oxygen Transport Hematology: Hemoglobin and Oxygen Transport Hard MEDICAL Confidence: high