A. A 3 season boot is a boot with a stiffer sole but with enough flex in it to cope with uneven ground whilst out hiking. These boots can be either leather or fabric and will have a waterproof and breathable membrane. A 3 season boot will not officially take a crampon but might take a flexible walking crampon therefore this kind of boot can be used anywhere below the snowline.
Before attaching crampons please ensure that you seek professional advice. All crampons should be fitted by a trained professional.