A Key Discovery That Weakened the Davson-Danielli "Sandwich" Model of Cell

A key discovery that weakened the Davson-Danielli "sandwich" model of cell membranes was that:

A) membrane proteins form a solid sheet on either side of the phospholipid bilayer.
B) membrane proteins form a solid sheet separating the phospholipid layer.
C) the phospholipids do not associate with each other in the hydrophobic region of membranes.
D) membrane proteins were not uniform and did not form flattened sheets.
E) membrane proteins occurred in regular organized patterns on the surface of membranes.