A programmable irrigation valve was tested at three soil-clay percentages. The design must deliver between 48 mL and 55 mL in each soil condition. Data: Valve | 10% clay | 25% clay | 40% clay | Notes Pulse A | 54 mL | 50 mL | 44 mL | underwatered clay-rich soil Pulse B | 51 mL | 52 mL | 50 mL | consistent Pulse C | 58 mL | 54 mL | 49 mL | too much in sandy soil Pulse D | 46 mL | 49 mL | 53 mL | too little in sandy soil Which valve best meets the delivery requirement across all clay percentages?