Which of the following are true regarding amino acids? I. Amino acids have ... ...

Which of the following are true regarding amino acids? I. Amino acids have carboxyl group. II. Amino acids have high melting points. III. Some amino acids can have a net positive charge. IV. Some amino acids can have a net negative charge.
(A) I, III & IV only
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in 28. Amino Acids and Proteins