The correct answer is (A): Both assertion (a) and reason (r) are true, and reason (r) correctly explains assertion (a).
Leaching, a cooking method involving soaking or boiling vegetables in water, removes excess soluble minerals. This technique is beneficial for individuals with chronic kidney disease, as their kidneys struggle to excrete potassium and phosphorus. By reducing the levels of these minerals, leaching makes vegetables safer for consumption by patients prone to harmful mineral buildup.