In a file contains the line "I am a boy\r\n" then on reading this line into the array str using fgets(). What will str contain?

What is the purpose of "rb" in fopen() function used below in the code?
FILE *fp;
fp = fopen("source.txt", "rb");

What does fp point to in the program ?
#include<stdio.h>
int main()
{
    FILE *fp;
    fp=fopen("trial", "r");
    return 0;
}

Which of the following operations can be performed on the file "NOTES.TXT" using the below code?
FILE *fp;
fp = fopen("NOTES.TXT", "r+");

To print out a and b given below, which of the following printf() statement will you use?
#include<stdio.h>
float a=3.14;
double b=3.14;

Which files will get closed through the fclose() in the following program?
#include<stdio.h>
int main()
{
    FILE *fs, *ft, *fp;
    fp = fopen("A.C", "r");
    fs = fopen("B.C", "r");
    ft = fopen("C.C", "r");
    fclose(fp, fs, ft);
    return 0;
}

On executing the below program what will be the contents of 'target.txt' file if the source file contains a line "To err is human"?
#include<stdio.h>
int main()
{
    int i, fss;
    char ch, source[20] = "source.txt", target[20]="target.txt", t;
    FILE *fs, *ft;
    fs = fopen(source, "r");
    ft = fopen(target, "w");
    while(1)
    {
        ch=getc(fs);
        if(ch==EOF)
            break;
        else
        {
            fseek(fs, 4L, SEEK_CUR);
            fputc(ch, ft);
        }
    }
    return 0;
}

To scan a and b given below, which of the following scanf() statement will you use?
#include<stdio.h>
float a;
double b;

Out of fgets() and gets() which function is safe to use?

Consider the following program and what will be content of t?
#include<stdio.h>
int main()
{
    FILE *fp;
    int t;
    fp = fopen("DUMMY.C", "w");
    t = fileno(fp);
    printf("%d\n", t);
    return 0;
}

Which of the following true about FILE *fp

When fopen() is not able to open a file, it returns

Who is father of C Language?