Choose the word which is different from the rest.

Tricycle
Trident
Trifle
Tricolour E. Trilogy

The answer is C. Trifle.

A tricycle is a vehicle with three wheels. A trident is a three-pronged spear. A tricolor is a flag with three colors. A trilogy is a set of three books or films. A trifle is a dessert made with sponge cake, custard, fruit, and whipped cream.

Trifle is the only word that does not refer to something with three parts.