I have a limit question on my homework that I don't know how to do.

The limit represents the derivative of some functionf(x) at some numbera.

lim (tan(x) - 1) / ( x - (π/4))

x →π/4

I have to select all appropriatef(x) andafrom a list that was given for the answer. The list was:

f(x) = tan(x), a =π/4

f(x) = tan(x), a =π

f(x) = tan(x) - 1, a =π

f(x) = tan(x), a = 1/4

f(x) = tan(x) - 1, a = 1/4

None of these

How would I solve this question? Thanks in advance.