The Uncommon Amino Acid Selenocysteine Has an R Group with the Structure

The uncommon amino acid selenocysteine has an R group with the structure -CH₂-SeH (pK_a $\approx$ 5) .In an aqueous solution,pH = 7.0,selenocysteine would:

A) be a fully ionized zwitterion with no net charge.
B) be found in proteins as d-selenocysteine.
C) never be found in a protein.
D) be nonionic.
E) not be optically active.