问题：
[单选题]The capital allocation line can be described as the ( )
Ainvestment opportunity set formed with a risky asset and a risk-free asset.
Binvestment opportunity set formed with two risky assets.
Cline on which lie all portfolios that offer the same utility to a particular investor.
Dline on which lie all portfolios with the same expected rate of return and different standard deviations.
答案解析：