Answer:
Four peptide bonds
Explanation:
The structure of alanylglutamylglycylalanylleucine is shown below.
It has four peptide (CO-NH) bonds, marked in red.
A is wrong. there are two carboxyl groups (green): The C-terminal end of leucine and the sidechain of glutamic acid.
C is wrong. There is no sulfur in the compound.
D is wrong. There is only one free amino group (blue): at the N terminal end of alanine.
