Final answer:
The combination of market region and urbanization is the significant geographic variable responsible for the furniture retailer's success, as this led to a higher market density and exposure to a target audience in a metropolitan area with advantageous situation factors.
Step-by-step explanation:
The significant geographic variable responsible for the Texas-based furniture retailer's success is likely b. Market region and urbanization. This combination includes the retailer's strategic move to a densely populated metropolitan area, which has resulted in improved market density due to a higher concentration of potential customers within Dallas-Ft. Worth. This shift likely provided increased exposure and accessibility to a target audience that prefers the foldable tables and convertible sofas offered by the retailer, a product range well-matched to the limited space within many urban apartments.
Furthermore, the concepts of situation factors and site location advantages are also important here. Cities like Dallas-Ft. Worth offer a central location, a multitude of transportation options, and other competitive advantages that contribute to business success and are reflected in the retailer's improved sales figures after relocating.