Selenium Can Substitute for Sulfur in the Amino Acid Cysteine

Multiple Choice

Selenium can substitute for sulfur in the amino acid cysteine to make the amino acid selenocysteine because ________

A) sulfur and selenium both begin with s.
B) their atomic symbols are similar.
C) both have about the same atomic radius.
D) both have the same valence electron configuration.
E) both have about the same ionization potential.