While driving, if you need to use your cell phone, using a hands-free phone will keep your mind on driving you should pull over to use the phone it is risk-free to have the conversation in a low-traffic environment it is completely safe as long as you keep your eyes on the road?

The answer to fill in the blank in the question above is "make sure that your phone is a hands-free system" based on the paragraph' content. A hands-free system means that a person does not have to use his/her hand for operating the system. A person must use this system if he/she is in the driving situation to avoid a distraction to his/her focus.