Final answer:
The correct pronoun is 'our.'
Step-by-step explanation:
In this sentence, the correct pronoun to complete the sentence is our. 'Our' is a possessive pronoun that indicates belonging to the subject 'we'.
The pronoun 'our' is used to show that the responsibility of knowing the lines belonged to the group of people involved in the rehearsal.
Example: 'For the first rehearsal, our acting coach emphasized the importance of knowing the lines.'
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