How do scientists know that dark matter and dark energy exist even if we can not see them

We only know it's there because we can see the effect of its gravity. Scientists study dark matter by looking at the effects it has on visible objects. Scientists believe that dark matter may account for the unexplained motions of stars within galaxies. Computers play an important role in the search for dark matter information.

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explanation:

the correct answer is option b

behavioral response need communication and thus co-ordination at several levels such as interaction among cells, organ system and the entire organism.

behavioral response produces both internal and environmental stimulus.