Your vehicle must have at least one rear-view mirror which gives a view of the highway at least feet to the rear.

Your vehicle must have at least one rear-view mirror which gives a view of the highway at least 200 feet to the rear.
This distance is required to aid the drivers in gauging the distance between their vehicles with other vehicles behind them, so they could prevent collision during road curves or sudden breaks.

B) hypothesis. its guessing and your guess could be changed quickly based on the information.