讨论：请教一道关于本地变量和环境变量的问题？？

unix_engineers

题目如下：请教应该如何选择？？？

What is the difference between local and environment variables?
A. When an Environment variable is defined in a child process, the variable value is
passed back to the child\'s parent process, too.
B. Variable defined by the system administrator are environment variables; variables
defined by regular users are local variables.
C. Environment variable are copied to child processes; local variable values are
not.
D. Variable that are shared by all processes on a unix system are known as environmental
are known as environmental variables. Variables that are made available to single user\'s
processes are also known as local variables.