Operating systems in C

15.) Suppose a program has successfully opened a file object, fp, for reading a file from a disk drive and the program has created a buffer, my-but, of an appropriate size. Consider the following C function call. fread (my_buf, 1, BUFFERSIZE, fp); a) Explain why this function call may, or may not, cause a system call to the operating system. b) Suppose that the above function call causes a system call. Explain why the operating system may, or may not, initiate arn I/O operation to read data from the file on the disk drive