The writing format includes all but the following a) page layout b)document margins c)required headings d)writing purpose

I think that the answers is c

Yes it is why .. 

With reference to the solutions, following things may be noted1) homogeneous solutions comprises of single phase.2) heterogeneous solution comprises of more than one phase.3) in colloidal solution, solute is evenly distributed in solvent. in such system, it is difficult to separate solute and solvent.4) in suspension, there is an uneven distribution of solute in solvent. in such system, solute and solvent gets separated on standing long.    blood is a homogeneous and colloidal solution,salad dressing is a heterogeneous and suspension solution.