There are more people who are obese today than 20 years ago.

A．gainfully employed

B．upwardly mobile

C．excessively overweight

D．privately educated

有一种原则是对信息进行均衡、全面的防护，以提高整个系统的“安全最低点”的安全性能，该原则称为______。

A．木桶原则

B．整体原则

C．等级性原则

D．动态化原则