The tangent function on its domain cannot be inverted because it is not injective nor surjective. In spite of this, it can be inverted if you restrict the domain.
The domain will have to be such as the function does not have any point of discontinuity (hence, no vertical asymptotes) and strictly increasing or decreasing (hence, you cannot have two points that have the same y-coordinate).
The restricted domain will be [0 , π/2) ∪ (π/2 , π).
In this domain, the tangent function is always decreasing, therefore the correct answer is A) So that y = tan(x) is always decreasing
