A particle of mass \(m\) and positive charge \(+q\) is constrained to move in the \(xy\)-plane within a region of electrostatic potential given by \(V(x, y) = V_0 \big(2 - \cos(kx) - \cos(ky)\big)\), where \(V_0\) and \(k\) are positive constants. The particle is released from rest near the origin at a small initial displacement \((x_0, y_0)\), where \(kx_0 \ll 1\) and \(ky_0 \ll 1\). Which of the following expressions represents the angular frequency \(\omega\) of the particle's resulting small oscillations?