Which set of assumptions inherent in input-output analysis calls into question its overall validity?

Explanation

The assumptions are: (I) Technical coefficients remain constant, implying no substitution between inputs; (II) No externalities exist, so the combined impact of multiple activities equals the sum of individual effects; (III) Each commodity is produced by a single industry, and each industry produces only one product; (IV) There is no technological progress. These assumptions together (I, II, III, and IV) limit the validity of input-output analysis.