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.

Bollinger Bands are constructed by plotting:
Option A:a MACD line and a signal line.
Option B:a moving-average line with an uptrend line above and downtrend line below.
Option C:a moving-average line with upper and lower lines that are at a set number of standard deviations apart.

Answer: C