Concept:Evaluate the nested inverse trigonometric functions step by step using principal values.Explanation:Start with the innermost term, cosec−1(2).Since csc(4π)=2, the principal value is 4π.Multiply by 2: 2×4π=2π.Now evaluate the cosine: cos(2π)=0.Multiply by the coefficient 2: 2×0=0.So the original expression simplifies to cot−1(0).The principal value of cot−1(0) is 2π.Answer:2π, which corresponds to option A.