问题详情

Password is a secret series of(69)that enables a user to access a file, computer, or program. On multi-user systems, each user must enter his or her password before the computer will respond to(70). The password helps ensure that(71)users do not access the computer. In addition, data files and programs may require a password.
A．symbol
B．sign
C．characters
D．characteristic请帮忙给出正确答案和分析，谢谢！