JU feet higher at timer t = 6 and returned to the point of origin at time t = 12. Comment on the statements: A) The average rate of altitude change over the time period [0, 12] de- pends on how fast the climber was ascending. B) The average rate of altitude change over [0, 6] is equal to average rate of altitude change over [12, 6]. C) At some time during the trip the climber was ascending at a rate of 150 feet per hour. D) At all times during the ascent the climber was ascending at a rate of 150 feet per hour