Which of the Following Is the Best Definition of Principle

Which of the following is the best definition of principle of diversification?

A) A theory showing that the expected return on any risky asset is a linear combination of various factors.
B) A risk that affects at most a small number of assets. Also called unique or asset-specific risks.
C) A risk that influences a large number of assets. Also called market risk.
D) Positively sloped straight line displaying the relationship between expected return and beta.
E) Principle stating that spreading an investment across a number of assets eliminates some, but not all, of the risk.