The Upper Paleolithic Blade Technology Was More Efficient Than Levallois

The Upper Paleolithic blade technology was more efficient than Levallois because:

A) Levallois worked only on softer stones that could not maintain a sharp edge for very long
B) Upper Paleolithic blades were struck from prepared cores and therefore were of a predetermined form, whereas Levallois flakes were struck off haphazardly produced cores and their form was unpredictable
C) many more Upper Paleolithic blades than Levallois flakes could be removed from the same-sized core, producing more cutting edge from the same amount of stone
D) blades are sharper than flakes