Hello.
The answer is: Number
The pronoun must agree with its antecedent in number. Rule: A singular pronoun must replace a singularnoun; a plural pronoun must replace a plural noun. A pronoun should agree with its antecedent in person, number, and gender. Person refers to the quality of being, number distinguishes between singular and plural.
Have a nice day
a noun
jack and milly came to tea
jack is he,milly she and little susie? well that's me
An agent went rogue once an enemey killed his fam.
Genre
hope this helps! :))))