The correct answer is: B. delimit a section of code.
The braces that surround the code in a ‘C program are called curly braces, and they are used to delimit a section of code. A section of code is a group of statements that are executed together. The braces tell the compiler that the statements inside the braces are part of the same group.
The other options are incorrect. Option A is incorrect because the braces do not show what code goes in a particular function. The function declaration tells the compiler what code goes in a particular function. Option C is incorrect because the braces do not separate the codes from the constant. The constant declaration tells the compiler that a particular value is a constant. Option D is incorrect because the braces do not separate the source file from the subject file. The source file is the file that contains the C code, and the subject file is the file that contains the compiled C code.