What would happen to a cell if its plasma membrane lost its selective permeability?

If there's no selective permeability, the cell would be able to allow all substances into the cell, in other words, the cell will be "permeable".

Normally, the biological membranes have a selective permeability, that is to say, they let themselves through some substances more easily than others, quickly pass through the membrane, because they dissolve in the lipid bilayer.

*Hydrophobic substances rapidly cross the membrane because they dissolve in the lipid bilayer.

*The small polar molecules (like H2O and CO2) thanks to their small size, these polar molecules also cross the double lipid layer.

*Large molecules and ions pass through the membrane through specific transport proteins, such as uniport, symport or antiport.

the answer is a or when it says crossing over

true, i don't really know what you're asking but from the info you provided im guessing the answer is true.