<prompt> Annealing of gold foil is the process by whichContaminants are removed from the surfaceRigidity decreases and ductility increasesBoth ductility and proportional limit decreasesNone of the above  <response>: Because gold attracts gases that render it noncohesive, such gases must be removed from the surface of the gold before dental compaction. This process is usually referred to as degassing or annealing and is accomplished by application of heat. Degassing is the preferred term, because the desired result is to remove residual surface contamination although further annealing, resulting in additional internal stress relief or recrystallization, may also occur in this process. 