Answer:
C. Change "it" to "my backpack."
Step-by-step explanation:
"It" is referring to the backpack, as it is what is holding the books.
So when you change the sentence, it should be "my backpack" instead of it.
Here's what the sentence should look like: "I try to bring all my book to every class each day, but my backpack can't carry all of them without becoming way too heavy."
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I hope this helps!
-No one