Which word does NOT belong with the others?

The core, seeds, and pulp are all parts of an apple. A slice would be a piece taken out of an apple.

The wing, fin, and rudder are all parts of an airplane.

In this series, the letters progress by 1; the numbers decrease by 3.

This is a simple multiplication series. Each number is 2 times greater than the previous number.

This is a simple subtraction series; each number is 4 less than the previous number.

Fair, just, and equitable are all synonyms meaning impartial. Favorable means expressing approval.

Unique, rare, and exceptional are all synonyms. Beautiful has a different meaning.

Acute, right, and obtuse are geometric terms describing particular angles. Parallel refers to two lines that never intersect.

A circle, oval, and sphere are all circular shapes with no angles. A triangle is a different kind of shape with angles and three straight sides.

The scythe, knife, and saw are all cutting tools. Pliers are tools, but they are not used for cutting.