Final answer:
Concrete and wood should not be used together in framing due to incompatibility, as their different properties can cause structural issues when combined in a permanent way. Wood can be used as temporary formwork for concrete, but not as a combined structural component.
Step-by-step explanation:
The question asks why concrete and wood should not be used together when framing. The correct answer to this question is a. Incompatibility. Wood and concrete have different properties that can lead to issues when used in direct combination in framing. For instance, wood is an organic material that can expand and contract due to moisture and temperature changes. Concrete, on the other hand, is an inorganic material that is much less susceptible to these changes but can crack under stress. When combined, the differential movement between these two materials can cause significant structural problems, potentially leading to cracks in the concrete or deformation in the wooden frame. This is why wood is typically used as a temporary mold or formwork for concrete during construction, rather than as a combined structural component. Once the concrete has cured, the wooden formwork is removed. Using them together as simultaneous structural materials could compromise the integrity and safety of the construction.