Which of the following figures is the odd one out?

The correct answer is Option (2) → 

Compare the shaded parts with the unshaded parts. In three figures exactly half of the parts are shaded. Option (2) has one of its four parts shaded, not half, so it is the odd one out.

Option (1) — Incorrect. A circle divided into four parts, two of them shaded: half of the parts are shaded.

Option (3) — Incorrect. A hexagon divided into six parts, three of them shaded: half of the parts are shaded.

Option (4) — Incorrect. A circle divided into eight parts, four of them shaded: half of the parts are shaded.