Which of the following is an antiderivative of csc x cot x?

Which of the following gives the correct antiderivative of tan x for x in an interval where cos x ≠ 0?

Evaluate ∫ tan^3 x sec^2 x dx using an appropriate substitution.

Compute ∫ cos^4 x dx using power-reduction identities.

Compute ∫ sec^5 x dx using the reduction formula or integration by parts to reduce the power to known integrals.