Concept:Use inverse trigonometric definitions and Pythagorean identities to simplify the terms.Explanation:Let θ=tan−13.Then tanθ=3.Using sec2θ=1+tan2θ, we get:sec2(tan−13)=1+32=10.Let ϕ=sec−13.Then secϕ=3.Using tan2ϕ=sec2ϕ−1, we get:tan2(sec−13)=32−1=8.Now evaluate the expression:sec2(tan−13)−tan2(sec−13)=10−8=2.Answer:2 i.e. Option C.