Why Does a Starchy Food Like Bread Become Hard When

Why does a starchy food like bread become hard when it dries out?

A) In the absence of water, unbranched starch molecules aggregate together by forming hydrogen bonds.
B) Cellulose molecules in the cells aggregate in the absence of water.
C) The release of carbon dioxide from drying starch causes the food to harden.
D) The remaining water and heat cause the polysaccharide chains to bind together.
E) Mold growth interferes with α linkages, causing the food to harden.