Out of the four parts given below, which parts plays significant role in forming concentrated urine in human? (i) Loop of Henle (ii) Glomerulus (iii) Bowman's capsule (iv) Vasa recta

• A. (i) and (ii)
• B. (iii) and (iv)
• C. (ii) and (iii)
• D. (i) and (iv)