Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

Two analysts estimating the value of a non-convertible, non-callable, perpetual preferred stock with a constant dividend arrive at different estimated values. The most likely reason for the difference is that the analysts used different:
Option A:time horizons.
Option B:required rates of return.
Option C:estimated dividend growth rates.

Answer: B