Choose the Correct Answer from the List Below

Choose the correct answer from the list below. Not all of the answers will be used.
-The precursor for serine, cysteine, and glycine amino acid biosynthesis is _______________.

A) atmospheric nitrogen (N₂)
B) 3-phosphoglycerate
C) cumulative
D) nitrogen fixation
E) B₁₂
F) histidine
G) tetrahydrofolate
H) committed
I) pyridoxal phosphate
J) enzyme multiplicity
K) MoFe cofactor
L) ammonia (NH₃)