Your compute_metrics function is ready to go now, and you'll return to it when you setup your training.
Train

If you aren't familiar with finetuning a model with the [Trainer], take a look at the basic tutorial here!

You're ready to start training your model now! Load BERT with [AutoModelForMultipleChoice]:

from transformers import AutoModelForMultipleChoice, TrainingArguments, Trainer
model = AutoModelForMultipleChoice.from_pretrained("google-bert/bert-base-uncased")