Which main-sequence on the hertzsprung-russell diagram are the least massive? a.) yellow b.) blue c.) orange d.) red

D.) Red

Explanation:

A star's luminosity and surface temperature are its two most important observational properties and are related to its mass in the formation. A graph of luminosity against temperature produces the Herzprung-Russell Diagram. Its historical importance arises, not only because it allowed the observation that stars evolve, but because they have become extremely important in the study of stellar evolution.

This diagram owes its name to two astronomers: the Danish Ejnar Hertzsprung and the American Henry Norris Russell, who, independently, in 1911 found that in a diagram of this type the stars did not occupy a random position, but were mostly located in certain positions, according to its mass and its radius.

According to this diagram, the least massive sequence is that of red color.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!