Question:
The advisor told the President that he was resigning.

he
Answer:
The advisor
Question:
T-Mobile's data plan is better than AT&T's data plan since it does not cap data usage.

it
Answer:
T-Mobile
Question:
John appreciated Bill because he had been in need.

he
Answer:
John
Question:
Jerrica saw the guard as she snuck past.

she
Answer:

Jerrica