It shows the doer of the action.It comes before verb and indicates this action or work is done by it/him/her etc.Ex.Susan switched off the lights. Who switched off the lights? The answer is Susan (subject of the sentence)
Answer:
i finished the work i was doing
I would say that her hair looked wild.
All of the stated options are correct about the usage of quotation marks, except for C, indicating measurements in inches.