Use the Graph to Solve the Problem $f(x)= \begin{cases}53+3.8 t & \text { if } 0 \leq t \leq 7 \\ 79.6 & \text { if } 7<t \leq 10 \\ -5.4 t+133.6 & \text { if } 10<t \leq 15\end{cases}$

Use the graph to solve the problem.
-In one city, the temperature in Fahrenheit on a typical summer day can be approximated by the following function:
$f(x) = \begin{cases}53+3.8 t & \text { if } 0 \leq t \leq 7 \\ 79.6 & \text { if } 7<t \leq 10 \\ -5.4 t+133.6 & \text { if } 10<t \leq 15\end{cases}$
Here, $t$ represents the number of hours since 6 a.m. The graph of this function is shown below. At what time does it start to get cooler?

A) At 10 a.m.
B) At 4 p.m.
C) At 1 p.m.
D) At 3 p.m.