Answer:
The answer is D.
Explanation:
a) Plugging x = 18 gets numerator 0^2/18 = 0 that not continuous.
b) Plugging x = 18 the denomiator becomes a value/0 making it undefined.
c) Plugging x = 18 gets tan(2pi) = 0/1 which is 0
d) f(x) = 36 is should be a straight lines at y =36. I think. Best option is D.