Three slope fields—P, Q, and R—are sketched on identical x–y grids.
• In field P, segments on any vertical line x=k share the same slope.
• In field Q, segments on any horizontal line y=k share the same slope.
• In field R, segments have zero slope on both axes and change sign by quadrant.
Which pairing correctly matches each field with its differential equation?
(A) dxdy=x (B) dxdy=y (C) dxdy=xy
a) P \to B,\; Q \to A,\; R \to C
b) P \to C,\; Q \to B,\; R \to A
c) P \to A,\; Q \to B,\; R \to C
d) P \to A,\; Q \to C,\; R \to B