An investment advisor uses Mean$-$Variance Optimization $($MVO$)$ to construct client portfolios but becomes concerned after noticing unexpected portfolio allocations. Which of the following best explains a fundamental drawback of MVO that may lead to unintuitive or unstable portfolio recommendations?

Group of answer choices

MVO is highly sensitive to small changes in inputs such as expected returns, which can lead to extreme asset weightings.

MVO requires investor utility functions, which are subjective and non$-$quantifiable in practice.

MVO assumes low correlation between asset classes, which is rarely observed in global markets.