Could I change "her" for "their"?

[Henry]

English Grammar Tests, Elementary Level

ESL/EFL Test #101 "Possessive pronouns", question 9

......... hand shot up when the teacher asked for volunteers.

(a) Their
(b) Her
(c) Mine

English Grammar Tests, Elementary Level

ESL/EFL Test #101 "Possessive pronouns", answer 9

Her hand shot up when the teacher asked for volunteers.

Correct answer: (b) Her

Your answer was: correct
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Hello, my name's Henry. I've got a question to make:

Could I change "her" for "their" ?

Thank you in advance.

Best regards

Henry

[seeemilywrite]

I think you could Henry. both answers seem like they would be correct.

[Yankee]

I disagree.

I would definitely not say "Their hand shot up...".

Amy
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Amy
.
ESL teacher, translator, and a native speaker of American English