7 Find the derivative of the given function y = cosh(x3) + sech (x4) 3x2 sinhx3 + 3x2 sinhx3 sinh2x4 - 4x3 sinhx4 a. y' = 1 + sinh2x4 3x2 sinhx3 + 3x2 sinhx3 sinh2x4 - 4x3 sinhx4 b. y' = (1 + sinh2 x4) 2 3x2 sinhx3 + 3x2 sinhx3 sinh2x4 - 4x3 sinhx4 c.y'= 1 + sinh2x3 d. None of the above