A plate, of uniform thickness and uniform density, has shape in the \( x-y \) plane defined by the lines \( x=0, y=2 \), and curve \( y=\frac{1}{2} x^{2} \). The plate lies in first quadrant of \( x-y \) plane. Then the \( x \)-coordinate of centre of mass of this plate is:
(A) \( \frac{1}{2} \)
(B) \( \frac{3}{2} \)
(C) \( \frac{4}{3} \)
(D) \( \frac{3}{4} \)
