Past form means it happened in the past.
Breaking means it is happening now (present tense) and is incorrect.
Broken is an adjective not a verb and is therefore incorrect.
Broke is the correct choice because it is past tense. Think, if you said, "I broke the chair" it means you broke it in the past, not in the present or future.
Breaked is not a word.
"I can't come with you as I am too busy."
Answer:
I would go with choice c.
Explanation:
