What statement is executed in the main program?

The statement executed in the main program is designed to produce output to the console. In this case, the correct option is the one that includes correct syntax and functionality for a printf statement in C.

Using printf("Welcome to C!\n") shows the proper usage of the printf function, which is the standard way to print formatted output in C. The \n at the end of the string represents a newline character, ensuring that after printing "Welcome to C!", the cursor moves to the next line in the console. This is typically the desired behavior when outputting text.

The other options either lack proper formatting, contain incorrect function usages, or do not serve the purpose of correctly displaying output in the way that option D does. For example, one of the other options omits the necessary components of the printf function altogether, while another incorrectly uses scanf, which is meant for input, not output. Therefore, the most suitable and correctly functioning statement in the context of the main program's objective is the one that utilizes printf with the appropriate syntax for output.