 First, (A)–(D) are falsified by processes that cannot be built and used as computing devices. The most obvious example is (B). Blum et al.’s result is equivalent to demonstrating that all functions over denumerable domains—including the uncountably many functions that are not Turing-computable—are computable by Blum et al.’s “computing” systems, which are allowed to manipulate the exact values of arbitrary real numbers. Hence, (B) is radically false. But at the same time, this result has no direct practical applications, as there is no evidence that concrete physical systems can manipulate arbitrary real-valued quantities in the way that Blum et al.’s systems do.