What was the most important thing to occur in the first 50,000 years of the universe?
a. matter
c. mass
b. electromagnetic radiation
d. the doppler effect

Option B, Electromagnetic radiation

Explanation:

It was during this period , for the first time in 50, 000 years that the density of matter had surpassed the density of electron. It was found that at temperature of 16000 kelvin, the radiation get converted to matter . This era was termed as Matter Era or Atomic Epoch  in which the atom form remained intact and hence the the electrons remained attached to nuclei also it was found that Electromagnetic radiation decoupled during this phase.

Hence, option B is correct

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!