What is the defining characteristic of a main sequence star? o it is fusing hydrogen into helium in its core. o it is fusing helium into carbon in its core. o there are no longer any fusion reactions in its core.. o it is yellow.

Option (1)

Explanation: Main sequence stars refers to those stars that are formed due to the fusion of hydrogen atoms in order to form helium its core. This are initially comprised of dust, gases and interstellar particles. Example of main sequence star are T Tauri and the sun.

The extreme pressure that is generated due to its increasing temperature balances the gravitational force that helps in holding the star.

Thus, the correct answer is option (1).

analyze the map below and answer the question that follows.

what does the map above tell us about the endemity of typhoid fever?

a.

there is greater occurrence of the disease in the western hemisphere.

b.

there is greater occurance of the disease in the northern hemisphere.

c.

countries located in equatorial regions are more likely to have incidents of typhoid fever.

d.

typhoid fever is more rampant among caucasian populations.

within these regions are all the major types of biomes in the world. a biome is a community of animals and plants spreading over an extensive area with a relatively uniform climate. some diverse biomes represented in north america include desert, grassland, tundra, and coral reefs.