Which of the following was Einstein's Second Postulate to the Special Theory of Relativity? a The speed of light is constant and is independent of the motion of the source or the observer. b The laws of physics are the same in all frames of reference that are moving uniformly. c Waves had to have some medium to travel through. d A beam of light that traveled parallel to the aether would take longer than the beam that traveled perpendicularly to the aether