The correct answer is B.
Based on the question itself I would assume you’re not in a math class that would discuss the numbers behind this observation, but I can at least reference it. The idea behind this is called the Law of Sines, which compares the length of an opposite side to the angle that produced the side. Larger angles produce longer sides as long as the two sides attached to the angle remain the same length. In this case, BC and RS are equal to one another and AC and ST are equal to one another, so this theorem applies. If RT is longer than BA, is is known by the Law of Sines that angle S will be larger than angle C, or the conclusion posed by answer B.
Hope this helps!
