Ahuman lost at sea without fresh drinking water is effectively lost in an osmotic desert. why would drinking salt water be harmful

Drinking salt water is harmful because it messes up the salt concentration in each of your red blood cells. It over loads the salt in it and causes the cell to swell up and burst due to it trying to let in more water to balance the salt concentration out. 

Part A : This is because it helped transform the material into DNA, thereby causing the smooth strain transforming into nonvirulent strain.

Part B : They proved it by applying the transformation mechanics, which proved that DNA not the proteins that it is required to transform from smooth strain using DNA.

Hope this helps.