Explanation:

Let’s break this down:

- Look at the series: 1, 1, 3, 4, 5, 9, 7, 16, 9, 25, 11, ?

- If you split it, you’ll notice odd positions: 1, 3, 5, 7, 9, 11. Those all increase by 2.

- Even positions: 1, 4, 9, 16, 25—look familiar? They’re perfect squares (1², 2², 3², 4², 5²).

- After 25, next square is 36 (6²).

- So, for the missing spot (even position): it should be 36.

Options:

1. 17 – Not a square, doesn’t fit.

2. 36 = 6². That’s our pattern.

3. 49 = 7², but that’s too far ahead.

4. 37 – No reason for this.

Your pick: option 2 - 36