Which of the following sequences is NOT geometric?
2,6,18,54,...2, 6, 18, 54, ...2,6,18,54,...
−3,6,−12,24,...-3, 6, -12, 24, ...−3,6,−12,24,...
100,50,25,12.5,...100, 50, 25, 12.5, ...100,50,25,12.5,...
2,5,10,20,40,...2, 5, 10, 20, 40, ...2,5,10,20,40,...