A standard stair has five components: stringer, nose, tread, riser, and what else?

In the context of stair construction, the standard components typically include the stringer, nose, tread, riser, and landing. The landing is an integral part of a staircase as it serves as a level area at the top or bottom of a flight of stairs, or in between flights when there is a change in direction. It provides a safe and stable area for users to stand, move between levels, or make directional changes in their ascent or descent.

While the other terms listed may have relevance in the broader construction or structural aspects of stairs, they do not fit within the standard five components that define the basic structure of a stairway. The "post" typically refers to vertical support structures, "crotch" is not a commonly used term in stair nomenclature, and "banister" refers to the handrail or the protective railing that might run along the side of the stairway, rather than being a component of the stair structure itself. Therefore, the correct answer emphasizes the landing, which completes the collective understanding of the essential parts of a stair system.