问题如下：
Açor’s portfolio allocation for Njau is most likely optimized on the basis of:
选项：
A.a stated maximum level of volatility.
total portfolio mean–variance efficiency.
the results of the risk tolerance questionnaire.
解释：
A is correct. Açor uses the goal- based investing approach by allocating with a focus on Njau’s charitable pledge to Udhamini. With this method, she seeks to optimize Njau’s portfolio so that the pledge goal has a high probability of being met. Açor will set aside a required amount of funds to invest, and a mean–variance optimization will be run specifically for that portion of Njau’s portfolio. The funds will be invested to a stated maximum level of volatility to meet the charitable need.
老师，a stated maximum level of volatility 这个在goal-based 方法中是体现在哪里呢？谢谢
