What needs to be emphasized in this step when reading?
"Turn the two bottle assembly over, and place the assembly on a table with the filled bottle on top. Watch the water slowly drip
down into the lower bottle Now, rapidly rotate the bottles in a horizontal circle a few times. Observe the formation of a
funnel-shaped vortex..."
a. rapidly rotate the bottles in a horizontal circle c. both A and B
b. Watch the water
d. neither A nor B