Cocks and valves control or interrupt flow, and have internal passages arranged so that they can be restricted or closed: in cocks, by rotating the plug, and in valves, by lowering, raising or rotating a disc in relation to a seating surfaceAccording to the above sentence, which of the following statements is not true?（）

A. Flows of fluids can be restricted by both cocks and valves
B. There are seats in the internal passages of valves
C. A disc of valve only moves up and down
D. We can infer that there is a bore in cock ping