单选题：Unnamed pipes are tools for communication between processes?

Unnamed pipes are tools for communication between processes?@[A](1)
A. that have the same parent PID
B. that are parent and child
C. that have the same effective UID
D. without any limitation



A.that have the same parent PID
B.that are parent and child
C.that have the same effective UID
D.without any limitation


答案：A