]the theories on the origin and expansion of the universe have changed from time to time. which of these best explains why the theories about the universe change over a period of time? new scientific investigations lead to new theories modern scientists reject old theories in every century the universe evolves constantly and requires new theories to describe it the discoveries of all scientists in different centuries have to be incorporated

Option A

Explanation:

New scientific investigation about universe always comes up with new theories. This happens because of two reasons -  

a) The exact knowledge of universal phenomenon is not known which lead to continuous investigation and hence new laws come up every time when a study or research is done

b) Also some scientist believes that universe is continuously expanding and changing due to which our previous theories no longer fit the current observations.  

Hence, option A is correct

cell regulation is conducted by special proteins.

there are mainly three domains in biological classification namely; archaea, bacteria, and eukarya.

archaea includes all the prokaryotic cells which are characterized by their lipid membranes. they have branched hydrocarbon which is attached to glycerol through an ether linkage.

bacteria includes all the prokaryotic cells, the cell membrane of which are made up of the unbranched fatty acid chain. in addition, they are attached to glycerol through an ester bond.

eukarya includes all the eukaryotic cells, that is, the cells contain a nucleus and other membrane-bound cell organelles.

they can be autotrophic as well as heterotrophic, unicellular as well as multicellular

they include kingdoms like protista, plantae, animalia, fungi et cetera.

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explanation: