Step 1: Use 3D section formula.
Let ratio \(r= m:n\).
Step 2: Point coordinates of division:
\[
x=\frac{–2n+3m}{m+n},\;
y=\frac{4n–5m}{m+n},\;
z=\frac{7n+8m}{m+n}.
\]
Step 3: Substitute in plane equation and solve linear relation → gives 3:7.
Hence → (C).