Find the value of 'x' in the following number series :
1, 2, 4, 4, 7, 6, 10, 8, x, 10, 16, 12.

1, 2, 4, 4, 7, 6, 10, 8, x, 10, 16, 12

Logic:
The series is divided into two parts:

Odd positions form an increasing series with a difference of +3.

Even positions form an increasing series with a difference of +2.

Odd-position terms: 1, 4, 7, 10, x, 16
=> 1 + 3 = 4, 4 + 3 = 7, 7 + 3 = 10, 10 + 3 = 13, 13 + 3 = 16
So, x = 13.

Even-position terms: 2, 4, 6, 8, 10, 12
=> Each term increases by +2, confirming the pattern.

Thus, correct option is (d).