与起搏器寿命有关的因素不包括（）。

A.主要由起搏器的电池决定

B.与耗电量有关

C.与起搏器工作的百分比有关

D.与起搏阈值有关

E.与起搏器体积大小有关

An analyst does research about portfolio management. Which of the following statements is Least accurate when an investor diversifies a portfolio（）

A. Systematic risk is eliminated.

B. The variance of the portfolio declines.

C. The portfolio will have a higher correlation with the market portfolio.