Which type of court is bounded on all sides by building lines?

The inner court is defined as a type of court that is surrounded on all sides by building lines. This construction design typically allows for light and air to enter the adjoining structures while also providing a private outdoor space for the occupants. This design is commonly found in urban environments where maximizing the usable area while maintaining necessary zoning regulations is essential.

In contrast, an open court is typically not enclosed by buildings on all sides, allowing for more openness and accessibility. A through court may either connect two different sides of a property or provide access through to a public area, while a corner court is specifically situated at the corner of two intersecting buildings. These types do not have the enclosed characteristics defined for an inner court. Thus, the nature of the inner court is what distinguishes it as the correct answer.