The execution of a C program always starts from the `main()` function. The `main()` function is a special function in C programming that serves as the starting point for the execution of the program. When the program is run, the control first enters the `main()` function and executes the statements inside it.

Here's a detailed explanation of why the `main()` function is the starting point of a C program:

1. Syntax: The `main()` function is defined with a specific syntax. It is defined as follows:
```
int main()
{
// statements
return 0;
}
```
The `int` before `main()` indicates that the function returns an integer value. The `return 0;` statement is optional and is used to indicate a successful execution of the program.

2. Entry Point: When a C program is executed, the operating system looks for the `main()` function to start the execution. It is the entry point of the program, where the control first enters.

3. Execution of Statements: Once the control enters the `main()` function, it starts executing the statements inside it. These statements can include variable declarations, function calls, conditional statements, loops, and more.

4. Return Value: The `main()` function can also return an integer value. By convention, a return value of 0 indicates successful execution, while any other non-zero value indicates an error or abnormal termination of the program.

5. Command Line Arguments: The `main()` function can also accept command line arguments. It can be defined as `int main(int argc, char *argv[])` to receive arguments passed during program execution. This allows the program to receive inputs or parameters from the user.

In summary, the `main()` function is the starting point of a C program. It is where the control first enters and from where the execution of statements begins. Understanding the role of the `main()` function is essential in C programming as it sets the foundation for writing and running C programs.