[单选题]
An object undergoes simple :epr;ll7v/eco;p gj(harmonic motion. Th z8v3l.y b-4k 4.kcolw n,yzmvr6yk;o e graph shows how acceleration $a$ varies with displacement $x$ from the equilibrium position of the object.
Which of the following gives the displacement of the object when its kinetic and potential energies are equal?
A. $\sqrt{2}\,m$
B. 1 m
C. $\frac{\sqrt{2}}{2}$
D. $\frac{1}{2}$
