Which of the Statements Below Served as Evidence That Rotational

Which of the statements below served as evidence that rotational catalysis occurs in ATP synthase?

A) movement was directly observed in the electron microscope
B) a fluorescently labeled actin filament attached to the enzyme's ɤ subunit was seen to rotate when ATP was added to the enzyme which was fixed to a cover slip
C) circular dichroism revealed the movement
D) an inhibitor stopped the enzyme movement
E) atomic force microscopy showed the movement