|Question 17Verbal

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An emulsifier is a type of compound that _____ to stabilize an emulsion--a mixture of two or more liquids that otherwise would not easily blend together. In the cosmetics industry, emulsifiers like cetostearyl alcohol are commonly used to blend oil and water into homogeneous formulations, like lotions and perfumes.
Which choice completes the text so that it conforms to the conventions of standard English?
served
A
had served
B
serves
C
was serving
D