Which statement best describes how an existing theory is often affected by the development of new technology?

A.) An existing theory is thrown out and replaced with a completely new theory based on the new observations.
B.)An existing theory is modified so that it can explain both the old and new observations.
C.)An existing theory remains the same because a theory is a proven fact that is always true.
D.)An existing theory is kept unchanged while a new theory is developed to explain the new observations.