6. found in the upper right of the H-R diagram -- A
7. a very hot and very luminous star --- B
Explanation:
The red giant is a luminous star with a mass in the late period of its stellar evolution and as the outer atmosphere inflated and is tenuous and maks the radius much larger and the temperature up to the 5000k.
While the main sequence is the continuous and a distinctive and is a continuous band of the stars appears in the stellar colors and the brightness. The majority of the stars in the galaxy are formed by these stars and the sun is an example.
While the white dwarf is degenerated and is composed of the hot and the dim stars these have a high density and mass.
B. The Sahar desert. The people from the south east of the continent migrated to other parts of Africa but not north Africa because the Sahara was in their way. This led to the ottomans to easily lay claim to North Africa and develop a Islamic and Arabic like culture.
