Find the odd number / letters / word from the given alternative.

The answer is D. Beam.

A house is a building that is used for habitation. It is typically made of wood, brick, or concrete, and has a roof and walls. A wall is a vertical structure that supports the weight of a building or other structure. A roof is the covering of a building or other structure that protects it from the weather. A beam is a long, rigid piece of wood, metal, or concrete that is used to support a weight.

In the given options, all are parts of a house except beam.