which of the following statements about gravitational waves are true?
a. The emission of gravitational waves from merging black holes is predicted by Einstein's general theory of relativity.
b. The first direct detection of gravitational waves, announced in 2016, came from the LIGO observatory.
c. Two orbiting neutron stars or black holes will gradually spiral toward each other as a result of energy being carried away by gravitational waves.
d. The emission of gravitational waves from merging black holes is predicted by Newton's universal law of gravitation.
e. Although gravitational waves are an important theoretical prediction, we do not yet have any observational evidence that they exist.