Amino acids can be distinguished from one another by a) the number of r groups found on the amino acid molecules. b) the chemical properties of their r groups. c) the type of bond between the r group and the rest of the amino acid molecule. d) the chemical properties of their amino and carboxyl groups. e) the number of alpha carbons present in the amino acid molecules

The answer to your question is: letter B

Explanation:

A) the number of R groups found on the amino acid molecules.  The number of groups R is not consider to distinguished amino acids, they only have 1 R group so this answer is incorrect.

B) the chemical properties of their R groups. This is the right answer because of the chemical properties of R groups them will be the kind of reactions an amino acid have.

C) the type of bond between the R group and the rest of the amino acid molecule. The type of bond is not important most of them have the same bonding. This answer is not correct

D) the chemical properties of their amino and carboxyl groups. All amino and carboxyl groups have the same properties. This answer is not right.

E) the number of alpha carbons present in the amino acid molecules. This is not important so this answer is not correct.

d. the weight of the book