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.

A prolonged period of an official interest rate very close to zero without an increase in economic growth most likely suggests:
Option A:quantitative easing must be limited to be successful.
Option B:there may be limits to the effectiveness of monetary policy.
Option C:targeting reserve levels is more important than targeting interest rates.

Answer: B