Hello!
The graphs of sine and cosine are waves. Therefore, choice A and B are wrong.
The graph of f(x) = cot(x) is an inverse of f(x) = tan(x), so therefore the graph of f(x) = cot(x) has the lines similar to the graph above, but it's flipped.
So therefore, the graph shown above is choice C, f(x) = tan x.
