The three basic renal processes are glomerular filtration, selective reabsorption, and tubular secretion.The blood is filtered in the Bowman's capsule due to the high hydrostatic pressure by a process known as ultrafiltration.The glomerular filtrate when passes through the convoluted tubules, the useful components present in the filtrate are reabsorbed by selective reabsorption. Tubular secretion (movement from the peritubular capillaries into the tubules) is a pathway in addition to glomerular filtration for a substance to gain entry to the tubule.So, the correct answer is option A.