Which of the following best summarizes what we mean by dark matter? matter for which we have theoretical reason to think it exists, but no observational evidence for its existence. matter that we have identified from its gravitational effects but that we cannot see in any wavelength of light. matter that may inhabit dark areas of the cosmos where we see nothing at all. matter consisting of black holes.

Dark matter is a type of matter, whose composition is unknown and which corresponds to 80% of the matter in the universe. Its name refers to the fact it does not emit or interact with any type of electromagnetic radiation, being completely transparent throughout the electromagnetic spectrum.  

However, it interacts with the known matter through gravity.  

This means that, like gravity, dark matter can not be observed directly, however its existence is inferred through the movement of the stars and the cosmic dust within the galaxies.

it has to be b, about 97 percent.

energy can be converted from one form to another, but it cannot be created or destroyed in ordinary chemical or physical means. do not understand what you are asking but hope this