Please answer this correctly without making mistakes

Answer:
I believe it is Began, because of the information below.
Explanation:
In modern English “began” is the simple past tense of “begin” “he began to study for the test at midnight.” But the past participle form—preceded by a helping verb—is “begun.” “By morning, he had begun to forget everything he'd studied that night.
I got this information off the web, so do not copy the above, but from the information, I gathered I do believe it would be began. You can decide for yourself, but I hope this helps! Thanks and BRAINLIEST PLEASE!
I might be wrong, so please do tell me if I am!