Parallax and Masers Are Two Techniques for Measuring Distances in Astronomy

Parallax and masers are two techniques for measuring distances in astronomy. Although very different from each other, they share a characteristic that is different from the other main measuring techniques. This is that:

A) they can both be used to measure the same set of objects and can thus check each other.
B) the relative motion of the distant objects is not important, thus avoiding the complication of Earth's motion.
C) each is independent of the results of any other distance measuring technique.
D) only these two techniques are correct for relativistic as well as Newtonian situations.