What is Cygwin?
A.
Cygwin is a free C++ compiler that runs on Windows
B.
Cygwin is a free Unix subsystem that runs on top of Windows
C.
Cygwin is a free Windows subsystem that runs on top of Linux
D.
Cygwin is a X Windows GUI subsytem that runs on top of Linux GNOME environment
Explanation:
Cygwin is a Linux-like environment for Windows. It consists of two parts:
A DLL (cygwin1.dll) which acts as a Linux API emulation layer providing substantial Linux API functionality.
A collection of tools which provide Linux look and feel. The Cygwin DLL works with all non-beta, non "release candidate", ix86 32 bit versions of Windows since Windows 95, with the exception of Windows CE.