Which of the following best describes the major difference between UNIX fork()…

The correct answer is Option D. The fundamental difference lies in how each system handles process creation. UNIX's fork() creates a new process by duplicating the calling process, resulting in two nearly identical processes that share memory until one writes to it. In contrast, Windows CreateProcess does not duplicate the current process; instead, it loads a new executable from disk and creates an entirely fresh process with its own memory space. This distinction makes fork() efficient for immediate execution of existing code, while CreateProcess is designed to launch new programs. Option A is incorrect because fork() and CreateProcess create processes, not threads within the same process. Option B is false as their mechanisms differ significantly. Option C is wrong because fork() operates in both command-line and GUI environments on UNIX systems.