The correct option is B A√2
We know that,
For a particle executing SHM, about mean position x=0.
The total energy of the particle
E=12mω2A2
Kinetic energy of the particle
K=12mω2(A2−x2)
Potential energy of the particle
U=12mω2x2
If, K=U
12mω2(A2−x2)=12mω2x2
⇒2x2=A2
Then, x=A√2=0.707A
Thus, option (b) is the correct answer.