不是说without increase么？

问题如下：

A prolonged period of an official interest rate of zero without an increase in economic growth most likely suggests:

选项：

A.quantitative easing must be limited to be successful.

B.there may be limits to the effectiveness of monetary policy.

C.targeting reserve levels is more important than targeting interest rates.

解释：

A central bank would decrease an official interest rate to stimulate the economy. The setting in which an official interest rate is lowered to zero (the lowest value that could be targeted) without stimulating economic growth suggests that there are limits to monetary policy.

中文解析：

中央银行会降低官方利率以刺激经济。在不刺激经济增长的情况下，将官方利率降至零(可能设定的最低值)，这表明货币政策是有局限性的。