A tray of lasagna comes out of the oven at 200 degrees and is placed on a table where the surrounding room temperature is 70 degrees. the temperature T(in F) of the lasagna is given by the function T(t)=e^(4.86753-t) + 70, t is greater than 0, where t is time (in hours) after taking the lasagna out of the oven. At which of the following times is the lasagna cooling slowest?
A) 3 hours after
B) 5 hours after
C) 6 hours after
D) 7 hours after
E) 9 hours after