Here is the original item:
Because he had eaten a stack of twelve
pancakes,
(A) Emanuel
heard his stomach begin to rumble
(B) as it
processed the food. (C)
Gurgling loudly to protest the huge meal.
You wanted to do this:
Because he had eaten a stack of twelve pancakes. Emanuel
heard his stomach begin to rumble as it processed the food. Gurgling loudly
to protest the huge meal.
Adding a period after pancakes will make Because he had eaten a stack of twelve pancakes a fragment.
You might want to review the rules.