A freezer is set to keep the inside at a temperature of $-4\mathrm{.}0C.$ If the outside temperature is $22\mathrm{.}0C,$ what is the maximum coefficient of performance possible?

a$)-0\mathrm{.}15$

b$)-7\mathrm{.}8$

c$)10\mathrm{.}3$

d$)11\mathrm{.}3$