What best describes a Compatible mesh?

A compatible mesh is characterized by having nodes that are shared between adjacent elements, ensuring that the mesh is continuous across the boundary of the elements. In this context, option B is correct because it specifically states that elements on touching bodies have overlaying nodes. This establishes a direct connection between the elements, which is crucial for achieving accurate simulations and analyses, as it allows for proper transfer of loads, displacements, and other interaction effects between the elements.

In contrast, the other options describe scenarios that do not meet the criteria for a compatible mesh. Having only one type of element or being restricted to certain types of elements (like Shell or Solid) does not ensure that the mesh is compatible or capable of representing the interface between different bodies accurately. A mesh made entirely of a single Solid element does not account for the interactions with other elements, while multiple types or single types of elements do not address how nodes interact at the interface, which is essential for a compatible mesh.