What is coordinating conjunction?

[Hoamuahe]

English Language Tests, Intermediate level

ESL/EFL Test #733 "Grammar Tutorial: Avoid Verb Tense Shifts (2)", question 1

She works in a coffee shop and, therefore, ......... various types of specialty coffee and tea for customers.

(a) makes
(b) making
(c) make

English Language Tests, Intermediate level

ESL/EFL Test #733 "Grammar Tutorial: Avoid Verb Tense Shifts (2)", answer 1

She works in a coffee shop and, therefore, makes various types of specialty coffee and tea for customers.

Correct answer: (a) makes

Your answer was: incorrect
She works in a coffee shop and, therefore, making various types of specialty coffee and tea for customers.
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Please tell me why verb reduction is not suitable in this case?

[Mister Micawber]

Because there is a coordinating conjunction, 'and', requiring a full clause on both sides.
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Native English teacher at Mister Micawber's