A toy robot is programmed to move in a straight line across a desktop according to the equation$$x$=1115$t$3+3\mathrm{.}1$tx$=1115$t$3+3\mathrm{.}1$t$,$ where x is in inches and t is in seconds. At some point during the movement across the desktop, the robot is at rest. What is the robot's acceleration at this point?

Select one:

a$.$

$3\mathrm{.}5$ in$/$s$2$

b$.$

$11$ in$/$s$2$

c$.$

$5\mathrm{.}3$ in$/$s$2$

d$.$

$13$ in$/$s$2$