What you saw without staining the cells with Iodine solution.

The answer is d.potassium

Ch4 and ph3 are both covalent since they are composed both of non-metals.    ch4 is non- polar because of  london forces and has a geometry of tetrahedral  ph3 , on the other hand, is umbrella shaped polar and has dipole-dipole intermolecular force (imf) . since ph3 is polar, it has a stronger imf   

The answer is c - the principal of original lateral continuity. 

The answer this would be radiative zone