Run command automatically when files are copied into a directory

I have two folders called: A and B, in different paths on the same computer. When I add any new file(s) into folder A, I want to copy it to folder B automatically.

My folders:

/auto/std1/nat1/A
/auto/std2/nat2/B

What I currently do to copy the files:

cp -r A B

But I want this process to run automatically in the background for every new file and folder in A into B.

Added question/problem

While copying files I would like specific actions to be performed on certain files types, example: when I have a zip file in folder A, I would like it to unzip this file in folder B automatically.

This is on a CentOS 7` system.