A cardiovascular researcher is conducting a study to evaluate the relationship between folate levels and cardiovascular disease. The results of the study show that persons with lower folate levels have twice the risk of cardiovascular disease mortality than do those with higher folate levels. Which of the following enzymes is most closely related to the role of folate in lowering the risk of cardiovascular disease?

1. A)Homocysteine methyltransferaseGABARITO
2. B)Thymidylate synthase
3. C)Ribonucleotide reductase
4. D)Dihydrofolate reductase
5. E)Glycinamide ribonucleotide transformylase