The most natural and grammatically correct sentence is:
✅ “She was dancing the tango/ballet/salsa.”
Explanation:
• “Dancing the tango/ballet/salsa” is the most natural phrasing in English. “Dancing” is the verb, and “the tango” or “ballet” functions as the object. However, note that “ballet” is usually referred to without “the” (e.g., “She was dancing ballet.”).
• “She was doing tango/ballet/salsa.” sounds unnatural, especially with “tango” and “salsa.” The verb “do” is not commonly used with dance styles. However, “doing ballet” is somewhat acceptable in informal speech, though “dancing ballet” is better.
• “She was tango/ballet/salsa dancing.” is possible, but it sounds slightly less natural. “Salsa dancing” is commonly used as a compound phrase (e.g., “She enjoys salsa dancing.”), but in continuous tense, “She was dancing salsa.” is preferred.
Tips:
For the most natural phrasing, use:
✔ “She was dancing the tango.”
✔ “She was dancing ballet.”
✔ “She was dancing salsa.”