True or False: A program in C must contain at least one main function.

In the C programming language, the main function serves as the entry point for program execution. Every C program must have a main function where the execution begins, making it essential for the structure of any valid C program. Without a main function, the program would not compile or run correctly because the C runtime environment looks for this specific function to start executing instructions.

This is fundamental to the C language specification; it mandates that the structure of a C program includes this function to facilitate the process of execution. Therefore, the statement that a program in C must contain at least one main function is true, as it is a core aspect of how C programs are designed and executed.