Which of the following will correctly add the number 100 to each variable in the sales array? The x variable was declared using the int x = 0; statement.

a. while (x <= 4)
        x += 100;
//end while

b. while (x <= 4)
{
      sales = sales + 100;
      x += 1;
} //end while

c. while (sales < 5)
{
        sales[x] += 100;
} //end while

d. while (x <= 4)
{
       sales[x] += 100;
       x += 1;
} //end while