Examiner Monitored the paper distribution__________10 minutes.(select the appropriate question)

since

for

from

none

Examiner Monitored the paper distribution for 10 minutes.
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We use "for" to talk about a purpose or a reason for something:
in the above sentence "the examiner monitored the paper distribution for 10 minutes".
so we use the "for" preposition here because "the examiner" talk about his purpose (monitoring paper distribution )
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ND9-11-2022