Multiple choice Who proposed the relay pump theory of ascent of sap? J. C. Bose Goldewski Wastermaeir Strasburger Reveal answer Fill a bubble to check yourself B Correct answer Explanation In 1884, Goldewski gave the relay pump theory. According to him, ascent of sap takes place due to rhythmic change in the osmotic pressure of living cells of xylem parenchyma and medullary ray.