Discrepancy - Despite these improvements, however, the rate of mountain climbing injuries has doubled in the past ten years.
A Many climbers, lulled into a false sense of security, use the new equipment to attempt climbing feats of which they are not capable. - Can be the answer
B Some mountain-climbing injuries are caused by unforeseeable weather conditions. - We don't know whether the weather conditions are bad over the past time.
C Mountain climbing, although a dangerous sport, does not normally result in injury to the experienced climber. - Irrelevant to the discrepancy
D In the past ten years there have been improvements in mountain-climbing techniques as well as in mountain-climbing equipment. - This sentence has nothing to do with the discrepancy
E Although the rate of mountain-climbing injuries has increased, the rate of mountain-climbing deaths has not changed. - we are talking about injuries, not deaths