阅读下面短文，并借助上下文和插图补充所缺信息。每个空只能填写一个形式正确、意义相符的单词。

     One day my uncle was (1)______ a newspaper and learned that (2)______  were our friends. We should

get (3)______  well with them. He looked at his nice bird in the cage, and decided (4)______  let it fly back

home nature. He took the cage with the bird in it and went to a little hill near his house by (5)______. He

(6) ______ the door of the cage, and the bird (7)______  away quickly. Seeing this, my uncle felt very happy.

He went home with the empty (8)______. When he got back, he sat in a chair and (9)______  a rest. A

moment later , to his (10)______, he found the bird back in the cage.

许多黑客利用缓冲区溢出漏洞进行攻击，对于这一威胁，最可靠的解决方案是（）。

A．安装防火墙

B．安装用户认证系统

C．安装相关的系统补丁软件

D．安装防病毒软件