can anyone help me with providing an expalnation for each correct answer?

Question

Pronoun-antecedent agreement B
12a. When a driver wants to buy a new vehicle, he or she usually test drives them. 12b. When a driver wants to buy a new vehicle, he or she usually test drives it.
Pronoun-antecedent agreement B
13a. Most presenters spoke without looking at his or her notes.
13b. Most presenters spoke without looking at their notes.
Pronoun-antecedent agreement B
14a. You may rent a movie or a video game for just one night if they are new.
14b. You may rent a movie or a video game for just one night if it is new.
Pronoun-antecedent agreement with indefinite pronouns A
15a. Neither the mayor nor the council members have filed their reports.
15b. Neither the mayor nor the council members have filed his reports.
Pronoun-antecedent agreement with indefinite pronouns B
16a. Anyone who requests a copy of the game may have it for their video library.
16b. Anyone who requests a copy of the game may have it for his or her video library.

Answer 1

12... vehicle(singular) is the antecedent of the pronoun... "them" is plural; "it" is singular.

13. Again, "presenters" is plural.
"his or her" is singular; "their" is plural.

14. "or" means one or the other, not both; therefore the antecedent is singular. "they" is plural; "it" is singular.

15. If any part of the subject is plural, then the antecedent is considered plural... so the pronoun must then be plural.

16. "Anyone" is one not many...so it is singular. Therefore, you need a singular pronoun.

Answer 2

congress usally resists a president's attemp to encroach on what they consider their authority.