Concept:Trellis drainage develops where rivers follow parallel valleys cut through alternating hard and soft rock bands.
Explanation:In areas with alternate hard and soft rocks, the soft rock erodes faster, forming parallel valleys.
The hard rock remains as ridges between the valleys.
Main rivers flow along the soft rock valleys, and smaller tributaries join them at right angles.
This creates a rectangular or grid-like pattern, which is called a trellised drainage pattern.
Therefore, the best drainage pattern in such a region is trellised.
Answer:A. trellised