Albert Einstein, the creator of the theory of relativity, initially believed that the universe was static. He changed his mind as a result from a tortuous thought process. Thus, he applied his model by which the universe is spatially curved and time-relative, that is, depends on the reference coordinating system. Such an interpretation would have a major problem, if the gravitational force was the only force, such a universe would collapse. He solved this by introducing the cosmological constants. Thus, space and time, as well as all measurements are subject to relativity and are not fixed.
The answer is: d.
