Which item is included in a typical bathroom group?

A typical bathroom group is defined as a collection of plumbing fixtures that serve a bathroom area. Among these fixtures, the lavatory stands out as a primary component. The lavatory is essentially a sink designed for hand-washing and other personal hygiene activities, making it integral to the functionality of a bathroom.

In contrast, the other options do not belong to the standard bathroom group. A kitchen sink is intended for food preparation and dishwashing, thereby placing it in the kitchen category rather than the bathroom. A water heater is a separate appliance that supplies hot water and is not a fixture within the bathroom itself. An outdoor faucet, designed for external use such as watering gardens or washing cars, does not fit within the indoor bathroom setup. Thus, the inclusion of the lavatory is what accurately represents a crucial element of a bathroom group.