A、In equity securities. B、In personal funds. C、In securities rated as investment grade. D、In property markets. C根据女士的回答商业银行只能投资

W: I know there are some elements which will affect the investors’ searches for the highest possible returns. What are they?
M: Risk aversion, lack of time, lack of skill, and other mortal conditions.
Q: Which of the following doesn’t belong to the elements which will constrain the investors’ searches for the highest possible returns?

M: It is reported that in some countries banks are not allowed to make investments in equity securities.
W: Generally commercial banks may invest only in those securities that are rated as "investment grade", or have bond ratings in the top four categories.
Q: Where are banks only allowed to make investments?