Correct Answer: 19

Solution : Given:

7, 2 = 59 ; 5, 3  = 28; 9, 1 = 810 ; 2, 1 = 13;

The given series adheres to the following pattern:

7, 2 = 59 →(7 – 2) × 10 + (7 + 2) × 1 = 59

5, 3  = 28 → (5 – 3) × 10 + (5 + 3) × 1 = 28

9, 1 = 810 → (9 – 1) × 10 + (9 + 1) × 1 = 810

2, 1 = 13 → (2 – 1) × 10 + (2 + 1) × 1 = 13

Similarly, 5, 4 = 19 → (5– 4) × 10 + (5 + 4) × 1 = 19

Hence, the first option is correct.