Step 1: Ultisols, low base saturation. Vertisols, shrink-swell clays.
Step 2: Mollisols, organic-rich dark surface horizon. Alfisols, higher base saturation, well-developed horizons.
Step 3: Match each order to its unique diagnostic feature.
Step 4: Correct option, (A)-(III), (B)-(II), (C)-(I), (D)-(IV).