Which structural feature distinguishes hemoglobin from chymotrypsin?

• A. Chymotrypsin is a heterotetramer, while hemoglobin is not.
• B. Chymotrypsin contains a heme group, while hemoglobin does not.
• C. Both hemoglobin and chymotrypsin contain prosthetic groups.
• D. Hemoglobin contains a heme group, while chymotrypsin does not.

Answer: (D)