A is correct. this is because more than one person was listening to the radio (my friend AND her mom) so you would use were as a plural tense rather than was because was refers to only one person using the radio. i hope this helped!!!!
A is correct because "my friend and her mother" can be substituted by the pronoun "they" which is plural, therefore the plural verb needs to be used, which is "were".
The correct sentence showing subject-verb agreement is A: 'My friend and her mother were listening to the radio,' because it uses the plural verb 'were' to match the plural subject. Sentence B is incorrect as it uses the singular verb 'was' for a plural subject.
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