Explanation:

Let's examine the pattern:

- For the set (9, 55, 64):

- 9 multiplied by 6 is 54, and 54 plus 1 is 55. Then, 55 plus 9 is 64.

- For the set (7, 43, 50):

- 7 multiplied by 6 is 42, and 42 plus 1 is 43. Then, 43 plus 7 is 50.

Now, let's analyze each option:

- Option 1: (7, 42, 50)

- 7 multiplied by 6 is 42, but 42 plus 7 is not 50.

- Option 2: (8, 32, 41)

- 8 multiplied by 4 is 32, but 32 plus 8 is not 41.

- Option 3: (4, 17, 21)

- 4 multiplied by 4 is 16, and 16 plus 1 is 17. But 17 plus 4 is not 21.

- Option 4: (5, 31, 36)

- 5 multiplied by 6 is 30, and 30 plus 1 is 31. Then, 31 plus 5 is 36.

Thus, the correct set is:

- Option 4: (5, 31, 36)