Concept:The principal value range of y=tan−1x is the open interval where tany is defined and one-to-one.Explanation:For y=tan−1x, we have x=tany.The tangent function is one-to-one on the interval −2π<y<2π.The endpoints ±2π are not included because tany is undefined there.Therefore, the range of y=tan−1x is −2π<y<2π.Answer:Option C: −2π<y<2π