252-81 Evaluate the integral: dx 4 (A) Which trig substitution is correct for this integral? Or = 81 sec(0) Ox=9tan(0) Or = 9 sin(0) Ox = 25 sin (0) Ox=81 tan(0) Or = 9 sec(0) (B) Which integral do you obtain after substituting for and simplifying? Note: to enter 0, type the word theta. de (C) What is the value of the above integral in terms of ? +C (D) What is the value of the original integral in terms of a? + C