Which of the given rotation curves in the figure below represents what astronomers would expect if dark matter did not exist in the halo of a spiral galaxy?
A) Rotation curve A
B) Rotation curve B
C) Rotation curve C
D) None of the curves would be correct.

Question

Which of the given rotation curves in the figure below represents what astronomers would expect if dark matter did not exist in the halo of a spiral galaxy? 
A) Rotation curve A 
B) Rotation curve B 
C) Rotation curve C 
D) None of the curves would be correct.

Quizplus · Accepted Answer

Rotation curve B represents what astronomers would expect if dark matter did not exist in the halo of a spiral galaxy. It shows a steady decline in velocity as the radial distance from the center of the galaxy increases, which is consistent with the gravitational effects of visible matter alone. Rotation curves A and C both show unexpected high velocities at large distances from the center, which implies the presence of unseen mass, such as dark matter.

Which of the Given Rotation Curves in the Figure Below