The motion of a particle is expressed by the equation a = -bx, where x is the displacement from the mean position, a is the acceleration and b is a constant. The periodic time is ………
(a) \(\frac{2π}{b}\)
(b) \(\frac{2π}{\sqrt b}\)
(c) \({2π}{\sqrt b}\)
(d) \(2\sqrt{\frac{π}{b}}\)