The PK₁,pK₂,and PK_R for the Amino Acid Histidine Are 1 $\alpha$

The pK₁,pK₂,and pK_R for the amino acid histidine are 1.8,9.3,and 6.0,respectively.At pH 4.0 would be charged predominantly as follows:

A) " $\alpha$ -carboxylate +1, $\alpha$ -amino 0,imidazole −1,net charge 0"
B) " $\alpha$ -carboxylate −1, $\alpha$ -amino +1,imidazole 0,net charge 0"
C) " $\alpha$ -carboxylate +1, $\alpha$ -amino +1,imidazole −1,net charge +1"
D) " $\alpha$ -carboxylate −1, $\alpha$ -amino +1,imidazole +1,net charge +1"
E) " $\alpha$ -carboxylate 0, $\alpha$ -amino +1,imidazole +1,net charge +2"