A hot liquid is placed in a refrigerator to quickly cool down. The temperature of the liquid can be modeled with the exponential function T=a(b)^m where m is the number of minutes it has been cooling. Based on the graph below, which of the following is closest to the value b for this model?
1) b=0.65
2)b=0.84
3)b=1.28
4)b=2.17