Question:
The hippo ate the food the trainer brought when he put it in the trough.

he
Answer:
the trainer
Question:
The mouse ran from the cat all the way to the kitchen because it was scared.

it
Answer:
The mouse
Question:
The rock melted in the lava because it was hot.

it
Answer:
the lava
Question:
Johnny Cage had to trick Scorpion into stretching himself out too thin since he had abilities which gave him the advantage.

he
Answer:

Scorpion