Exercise 3: sample answer

Safety: the rider sat low with feet able to reach the ground, so there was no header from a great height, and mounting was easy. Comfort and price: pneumatic tyres smoothed the ride, and mass production lowered prices, so ordinary people, including women and older riders, could afford and use one (check). Either of these, with one supporting detail, is a good answer; the lower seat also meant no special skill or athletic build was needed.