Jane and mark make an h-r diagram and conclude that the sun is the brightest and hottest star within 20 light years of earth. do you agree with their claim? why or why not?

No

Explanation:

Sirius A is the brightest, hot star nearest to Earth next to the Sun. It is about 8.6 light years away. It has 98% mass of the Sun confined in size smaller than our Earth. It has a surface temperature of 9940 K which is much greater than the surface temperature of the Sun (5800 K).

Thus, Jane and Mark's claim is incorrect that the Sun is the brightest and the hottest star within 20 light years of the Earth. The Sun is the brightest because of its proximity but not the hottest.

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).