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Please advise which of the following is correct and why:

Mary suggested that they wear a hat.

Mary suggested that they wear hats.
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Since it is common shared knowledge that each person normally wears one hat, either sentence will serve. If you wish to be consistent, keep people and hats in the plural.
Comments  
Ethanw
Please advise which of the following is correct and why:

Mary suggested that they wear a hat.

Mary suggested that they wear hats.

Answer: Mary suggested that they each wear a hat.

Comments: The first sentence implies they share a hat.

The second sentence implies they wear more than one hat.

The suggested sentence clears the ambiguity.
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 Mister Micawber's reply was promoted to an answer.
Mary suggested that they wear hats.

They is plural so do hats
Many thank. It's good to share and to get an direct answer.
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