6. What is one way in which scientists study dark matter?
O A They study how light bends around a galaxy or
galaxy cluster.
OB They study shadows that are cast onto a galaxy
or galaxy cluster.
OC They study changes in the number of galaxies in
a galaxy cluster.
OD They study how the brightness within a galaxy or
galaxy cluster changes.

Based on the cause-and-effect relationship in this sentence, what is the meaning of the word revert? the brownies kali made using a new recipe were too dry, so she reverted to her original recipe. a) to alter or change completely; revise b) to dispose of or remove; to throw away c) to prepare for something; assemble or make d) to go back to a previous state or practice