IQ Test · Adults Question 19

What number should replace the question mark? Array 1: 7 4 6 / 2 8 9 / 3 1 7. Array 2: 8 4 7 / 2 9 9 / 4 1 8. Array 3: 8 3 7 / 1 9 8 / 4 ? 8. Answer with a natural number.