The advanced technology of ski boots and bindings has brought a dramatic drop in the incidence of injuries that occur on the slopes of ski resorts: from 9 injuries per 1, 000 skiers in 1950 to 3 in 1980. As a result, the remainder of ski-related injuries, which includes all injuries occurring on the premises of a ski resort but not on the slopes, rose from 10 percent of all ski-related injuries in 1950 to 25 percent in 1980. The incidence of these injuries, including accidents such as falling down steps, increases with the amount of alcohol consumed per skier. Which one of the following can be properly inferred from the passage? ['Injuries that occurred on the slopes of ski resorts made up a smaller percentage of ski-related injuries in 1980 than in 1950.', 'As the number of ski injuries that occur on the slopes decreases, the number of injuries that occur on the premises of ski resorts increases.', 'If the technology of ski boots and bindings continues to advance, the incidence of ski-related injuries will continue to decline.', 'The technology of ski boots and bindings affects the incidence of each type of ski-related injury.']