What type of land is used to separate different land uses, such as residential and commercial?

The correct answer is buffer zone. A buffer zone is specifically designated land that serves to separate different types of land uses, such as residential from commercial. This zoning technique is employed in urban planning and development to minimize conflicts between incompatible land uses, enhancing the quality of life for residents while also ensuring that commercial entities can operate effectively without disruption from residential areas.

In contrast, a transition zone generally refers to an area that is in the process of changing from one type of use to another, which might include a mix of uses but does not serve the specific function of separation. Residential and commercial zones refer to specific areas designated solely for either residential or commercial use and do not inherently provide separation between these distinct uses. Therefore, while they define where certain activities can occur, they do not function to separate those activities from each other the way a buffer zone does.