Step 1: Subject–verb agreement
The subject “The best part” is singular, so the correct verb form is “is,” not “are.”
Step 2: Plural noun usage
The noun “dances” is plural and correctly follows the singular subject via the linking verb “is.”
Step 3: Eliminating incorrect options
- (b) uses “are” incorrectly with singular subject.
- (c) has “dance” (singular) after “are,” which is incorrect in meaning and grammar.
- (d) changes subject to plural “parts,” which alters intended meaning.
Thus, option (a) is grammatically correct and preserves intended meaning.