Which type of dwelling is characterized by being connected to one or more other units by common walls?

The correct answer is a town house. This type of dwelling is specifically designed to be connected to one or more neighboring units through shared walls. Town houses are typically part of a row of similar structures, allowing for efficient use of land and shared utilities while providing residents with individual living spaces.

In contrast, an apartment is usually part of a larger building where multiple units are rented, and each unit is separate but may share common areas. A condominium, while it may have shared walls similar to a town house, typically refers to a type of ownership rather than a specific building style, where individuals own their unit but share common areas. A single-family home, on the other hand, is a standalone structure that is not connected to any other dwelling, providing privacy and independence from neighbors. Therefore, the key characteristic of a town house being connected by common walls correctly differentiates it from the other options provided.