Multiple Choice
Spiral structure:
A) rotates at the same speed as the gas in the disk
B) rotates at a speed that is different than the gas in the disk
C) stays constant in time as the gas in disk rotates through it
D) rotates backward compared to the stellar orbits
E) must only last a short time, since few galaxies with disks show spiral patterns
Correct Answer:

Verified
Correct Answer:
Verified
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