In an operating system, which of the following system calls is most likely to cause a process to enter a waiting state due to synchronization with another process? 

The wait() system call is used by a process to wait for the termination of a child process. When a process calls wait(), it enters a waiting state until one of its child processes exits. This is a synchronization mechanism that ensures that the parent process doesn't proceed until the child process has finished execution. In scenarios involving inter-process communication or concurrency, wait() is vital for preventing race conditions and ensuring correct process sequencing. The parent process will be suspended until the state of the child process changes, hence entering a waiting state. Why Other Options are Incorrect: A) fork(): fork() creates a new process but doesn't cause the parent or child process to wait; they execute concurrently. B) exec(): exec() replaces the current process's memory space with a new program but doesn't cause a process to wait. D) exit(): exit() terminates the current process but doesn't result in a waiting state for the process calling it. E) signal(): signal() is used to send a signal to a process but does not inherently involve process synchronization or waiting.