Tom begins a hike at an elevation of 6,000 feet. tom's elevation, at any time, is shown on the graph below. which statement is true? a. the elevation tom is at always decreases compared to the time. b. tom decreases in elevation by that same amount every hour for the last three hours. c. tom walks at all times, for the entire hike. d. tom never changes more than 1,000 feet of elevation per hour.