• Slope Limits for Irrigation in Light (Sandy) Soils:
• Light-textured (sandy) soils have high infiltration rates and low cohesion, making them highly susceptible to sheet and rill erosion during overland flow.
• In surface irrigation systems (such as contour furrows or border strips across the slope), light soils can be irrigated safely across slopes up to 5% without severe scouring erosion.
• Above 5%, pressurized sprinkler or drip irrigation must be adopted.
• Conclusion: 5% (Option 3).

Correct option: (3) 5%

• Classification of Irrigation Efficiencies:
• Water Conveyance Efficiency ($\eta_c$): Ratio of water delivered to the farm fields to water diverted from the source canal network: $\eta_c = (W_f / W_d) \times 100$. (True)
• Water Application Efficiency ($\eta_a$): Ratio of water stored in the crop root zone during irrigation to water delivered to the field, directly governed by the irrigation method (surface, sprinkler, drip). (True)
• Economic Efficiency: Evaluates overall economic returns generated per unit cost/volume of irrigation water across the system. (True)
• Conclusion: (A), (B) and (C) are all correct (Option 4).

Correct option: (4) (A), (B) and (C).

• Mechanisms of Sediment Transport in Streams:
• Bed load consists of coarse particles moving in contact with or near the channel bed by rolling, sliding, and saltation (bouncing). (True)
• In natural alluvial rivers, bed load typically constitutes less than 10% to 25% of the total sediment load, while suspended load constitutes 75% to 90%. (True)
• Suspended load is measured directly in streams using depth-integrating (e.g., US DH-48) or point-integrating samplers. The statement says it is not measured, which is False.
• Conclusion: Statements (A) and (B) only are correct (Option 1).

Correct option: (1) (A) and (B) only.