Place the Following Steps in Their Proper Order Starting with DUMP

Place the following steps in their proper order starting with dUMP and N⁵,N¹⁰-methylenetetrahydrofolate as substrates.
1) Formation of tetrahydrofolate
2) Formation of N⁵,N¹⁰-methylenetetrahydrofolate
3) Formation of 7,8-dihydrofolate

A) 2; 1; 3
B) 1; 3; 2
C) 1; 2; 3
D) 3; 1; 2