When you say narrower, it means that the range would be slimmer. Hence, it would be logical to choose the function in which the value of f(x) would decrease. Try substituting values for x to the functions in the choices. If the answer is less than the value of x you chose, then that is the answer. The acceptable answers would be:
The term is less than. Think about it this way next time, the mouth is open to the bigger number because it wants to eat the bigger number. So the number facing the tail is always less than.
