Which is a complete list of factors of each term in the expression 15 + 20 x? 15: 1, 3, 5, 15 20x: 1, 2, 4, 5, 10, 20, x 15: 1, 3, 5, 15 20x: 1, 2, 4, 5, 10, 20 15: 3, 5 20x: 4, 5, x 15: 1, 3, 5 20x: 1, 2, 4, 5, 10, x