why is the verb dance in Past Indefinite?

[Milly]

English Language Tests, Intermediate level

ESL/EFL Test #733 "Grammar Tutorial: Avoid Verb Tense Shifts (2)", question 3

While the music plays in the plaza, people ......... around and enjoy the evening, summer weather.

(a) danced
(b) dance
(c) dancing

English Language Tests, Intermediate level

ESL/EFL Test #733 "Grammar Tutorial: Avoid Verb Tense Shifts (2)", answer 3

While the music plays in the plaza, people danced around and enjoy the evening, summer weather.

Correct answer: (a) danced

Your answer was: incorrect
While the music plays in the plaza, people dance around and enjoy the evening, summer weather.
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why is the verb dance in Past Indefinite, while the other verbs plays and enjoy are in the Present Indefinite?

Milly

[Mister Micawber]

There is a typographical error in the test, and we will soon fix it. Thank you for bringing it to our notice. 'Dance' is the correct answer.
_________________
Native English teacher at Mister Micawber's

[Slava]

Ok. Corrected.
http://www.english-test.net/esl/learn/english/grammar/ii733/esl-answers.php#avoid_verb_tense_shifts_answer_three
Slava