Which sequence of formation is most likely to be correct, oldest to youngest?
A) globular clusters, open clusters, OB associations
B) Population I stars, population II stars, population III stars
C) halo, spiral arms, globular clusters
D) planetary nebulae, Population I stars, population II stars
E) emission nebulae, planetary nebulae, dark nebulae
Question 2
Contrast the compositions and heights of the clouds of Earth and Venus.
What will be an ideal response?