Considere as seguintes propostas de reescrita para o trecho ...
Considere as seguintes propostas de reescrita para o trecho But a slippery, porous slate no school-room or cottage roof could find use for (l. 36-38).
I - But a slippery, porous slate for which no school-room or cottage could find use
II - But a slippery, porous slate that no school-room or cottage could find use for
III- But a slippery, porous slate who no school-room or cottage could find use for
Quais poderiam substituir o segmento destacado, sem prejuízo do sentido literal e da correção gramatical?