In Children, There Are Nine Essential Amino Acids but in Adults

In children, there are nine essential amino acids but in adults there are only eight. What accounts for this?

A) Adults can synthesize enough of one amino acid that children cannot.
B) Children store one essential amino acid that they later use as adults.
C) Adults lose the ability to synthesize one amino acid that children can synthesize.
D) Adults have an amino acid transporter that children lack.