Which of the following statements is incorrect about the circulatory system of earthworm?

Options

A. Pheretima represents a closed type of blood vascular system
B. Blood glands are present in `4^(th), 5^(th) and 6^(th)` segments, they produce blood cells and haemoglobin dissolved in plasma
C. There are four pairs of hearts in earthworm present in 7,9,12 and 13 segments
D. In dorsal vessel blood flows in forward direction and without valves

Answer

D