Explanation:

Let’s break it down:

- Look at how 39 is related to 91.

- 39 × 2 + 13 = 78 + 13 = 91.

- Now try that with 51:

51 × 2 + 13 = 102 + 13 = 115.

- But 115 isn’t in the options. Let’s try a different pattern.

- Check if the jump from 39 to 91 is just an addition. 91 - 39 = 52. Doesn’t fit a clean pattern either.

- Now, look for another simple mathematical link. Is it a multiple? 39 × something = 91? No.

- Try this: 39 = 13 × 3, and 91 = 13 × 7.

- Both numbers are multiples of 13, and the second number’s factor (7) is four more than the first (3).

- So for 51: 51 divided by 17 = 3. So 51 = 17 × 3.

- Now try multiplying 17 by (3 + 4 = 7): 17 × 7 = 119.

Checking your options:

- Option 1: 119

- Option 2: 93 (17 × 5.47, not a whole number)

- Option 3: 178 (doesn’t fit)

- Option 4: 125 (17 × 7.35, not a whole number)

So, the answer is clearly 119.