C)
1) Examining that graph that relates the distance and the time of those club members in a ride.
2) Since at instant t= 3 hours and t=4 hours, the club members remained at the same distance and the time has continued to elapse.
The club members did not ride at a constant speed.
The number of miles did not decrease
3) We can state that the club members have stopped for a rest during one hour approximately when they kept at something around 30 and 40 miles from their starting point. Then the answer is :
C)