Option A is the correct one. Interval training is a mode of training where there are short intervals of intense exercise, followed by relief periods. This helps dynamic aspects like strength, speed and power. Option B relates to Endurance training or even intense aerobic training that have lower intensity and have a long duration. C is wrong; it is easy to see that no training programm can get you fit in 5 days! D is wrong since no training regime can guarantee that there will be no injuries; training regimes can only act as a precaution in order to reduce the probability of injuries.