Question

In nineteenth-century European architectural history, structural engineers encountered widespread opposition from academic purists regarding the integration of cast iron into public building frameworks. Theoretical detractors argued that cast iron lacked the tensile ductility of wrought iron, rendering structural elements dangerously vulnerable to sudden brittle fracture under asymmetric thermal expansion or localized impact. However, recent historical analysis of municipal treasury records and engineering logs reveals that municipal planning committees between 1840 and 1865 systematically selected cast iron for urban transit terminals and multi-tiered commercial halls. Contrary to the long-held assumption that this preference stemmed from technical negligence, municipal authorities prioritized cast iron primarily because of its exceptional compressive strength when enclosed within masonry piers, as well as its considerably lower founding and casting costs. Furthermore, while structural theorist Henri Dupin famously contended in an 1848 treatise that unreinforced cast-iron columns posed unacceptable structural risks in public edifices unless bound by exterior wrought-iron tension straps, municipal building inspectors consistently granted regulatory exemptions to single-story exhibition galleries. These exemptions were contingent upon foundational footings being anchored directly into solid bedrock substrates rather than unstable alluvial deposits. This distinct regulatory loophole allowed suburban commercial developers to bypass the expensive metallurgical stress testing normally compulsory for urban high-rise construction, accelerating suburban commercial expansion despite ongoing academic warnings.

According to the passage, municipal building inspectors granted regulatory exemptions regarding cast-iron reinforcement in single-story exhibition galleries under which of the following conditions?