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Option 2 seems right to me.

I go with this option.

Since she needs to go to the bathroom, I guess she can't hold it longer. So she has to ask for help from another teacher.

Since she has 20mins, she would not be able to hold it for to long. She has to seek for help from other teachers.

I go with this option

I'll choose this option.

I will choose option 2.

It's best she knocks on the teachers windows for help.

I choose this option

i will knock on the window ask a teacher to help and then go to the bathroom