Which of the Following Statements Explains Why Methotrexate Is Effective

Multiple Choice

Which of the following statements explains why methotrexate is effective as a cancer chemotherapeutic?

A) it serves as an analog of p-aminobenzoic acid and block bacterial synthesis of folate
B) acts as an inhibitor of dihydrofolate reductase, thus preventing production of tetrahydrofolate
C) it acts as a suicide substrates for the enzyme dihydropteroate synthetase
D) prevents the conversion of N⁵,N¹⁰-methenyl THF to N¹⁰-formyl THF which is required in 2 steps of the purine synthesis pathway
E) both b and d are correct