The word "appealing" most nearly means "attractive".
Something that is appealing is pleasing or interesting to the senses or mind. In the case of the singing voice, it is pleasing to the ears.
The other options do not have the same meaning as appealing.
- "Angry" means feeling or showing anger.
- "Annoying" means causing someone to feel annoyed or irritated.
- "Helpful" means providing assistance or doing something useful.