The correct structure of glycine at given `pH` are :
A. `H_(3) overset(oplus)(N)CH_(2)-underset(underset(O)(||))(C)-OH" "at pH=2.0`
B. `H_(3)overset(oplus)(N)CH_(2)-underset(underset(O)(||))(C)-O^(Theta)" "at pH=6.0`
C. `H_(2)NCH_(2)-underset(underset(O)(||))(C)-O^(Theta)`
D. `H_(2)NCH_(2)-underset(underset(O)(||))(C)-OH" "atpH=12`