According to the given poem, a house may have a yard.

Explanation:
The poem mentions that a house may have a yard. A yard is an open space that surrounds a house, typically covered with grass or other plants. It is a common feature of many houses and provides an outdoor space for various activities such as playing, gardening, or simply relaxing. The yard can be a place where children can run and play, families can have picnics or barbecues, and individuals can enjoy the fresh air and nature.

Having a yard is considered desirable for many homeowners as it provides a sense of privacy and a connection to the outdoors. It can be a space for creative expression through landscaping and gardening, allowing individuals to cultivate plants, flowers, or even grow their own vegetables. A well-maintained yard can enhance the aesthetic appeal of a house and create a welcoming atmosphere.

In addition to the yard, a house may also have other features such as a well or a tank. A well is a source of water, often located underground, which can be used for various purposes such as drinking, cooking, or irrigation. A tank, on the other hand, is a container or reservoir used for storing water or other liquids. These features are not explicitly mentioned in the poem but are commonly found in and around houses.

Therefore, the correct answer is option 'C' - a house may have a yard.