Which of the following is an 8-aminoquinoline?

• A. I, II
• B. I, III
• C. III only
• D. I, II, III

Answer: (C)

An 8-aminoquinoline is defined by having an amino group attached specifically at the 8-position of the quinoline ring. In quinoline, position 1 is the ring nitrogen, and position 8 sits on the fused benzene portion opposite it. This 8-position substitution is what distinguishes 8-aminoquinolines from other quinoline derivatives.

Among the three structures, only the third structure shows an NH2 group at that 8-position on the quinoline core, so it fits the definition of an 8-aminoquinoline. The other structures either lack the amino group at the 8-position or place the amino group elsewhere on the ring, so they do not belong to this class. Therefore, the third structure is the correct one.