Explanation:

Let’s break this series apart:

- First, look at the sequence: 13, 26, 23, 115, 108, ?

- See a pattern? There’s a kind of alternation going on.

- 13 doubles to 26 (13 × 2).

- 26 minus 3 gives you 23 (26 - 3).

- 23 × 5 = 115.

- 115 - 7 = 108.

Now, what should come next? The operations so far: ×2, -3, ×5, -7.

- Logically, the next step probably follows the pattern—alternate multiplication by an odd number, and then subtract an odd number, both increasing by 2 each time.

- So now, after -7, you’d multiply by 7.

108 × 11 = 1188

Here's a quick look at the options:

- 1118 (no, doesn't fit)

- 1818 (off by a ton)

- 1881 (wrong order, not matching pattern)

- 1188 fits perfectly.

So, the answer is 1188.