Biology · Excretory Products and their Elimination

In the context of mammalian nephron function, consider the following statements: 1. The ascending limb of Henle's loop actively transports Na+ and Cl- out of the filtrate but is impermeable to water. 2. The vasa recta surrounding the loop of Henle helps maintain medullary hyperosmolarity through countercurrent exchange. 3. The efferent arteriole emerging from the glomerulus always forms peritubular capillaries and vasa recta irrespective of nephron type. 4. The filtrate entering the distal convoluted tubule is hypotonic relative to blood plasma. Which of the above statements are correct?