Will give

which describes the sequence of events of the development of the universe?

big bang → star and galaxy formation → expansion and cooling → atom formation → continuation of expansion and cooling

atom formation → star and galaxy formation → expansion and cooling → continuation of expansion and cooling → big bang

atom formation → big bang → star and galaxy formation → expansion and cooling → continuation of expansion and cooling

big bang → expansion and cooling → atom formation → star and galaxy formation → continuation of expansion and cooling

big bang → expansion and cooling → atom formation → star and galaxy formation → continuation of expansion and cooling

aka, D.

Option D, big bang → expansion and cooling → atom formation → star and galaxy formation → continuation of expansion and cooling

Explanation:

It is believed that universe started with is big bang and the universe started from a hot, dense point. Just after the big bang, the universe is supposed to filled with neutrons, protons, electrons, anti-electrons, photons and neutrinos which then started  expanding. The expansion continued with a slower rate after a certain period of time.  The expanding universe became cool simultaneously and matter started forming.  

With lowering temperature, protons and neutrons fused to form deuterium which further produced hydrogen, then helium and also lithium.  

After some millions of year, the matter cooled extensively to form atom stars & galaxies. It also produced a transparent, electrically neutral gas.  

It is now believed that  a mysterious force named as dark energy is speeding the expansion of universe which is continuing even today.  

Hence, option D is correct

the answer is d. chordata