Biology question please explain why?

The cellular membrane is made up of a phospholipid bilayer with a hydrophilic head group and a hydrophobic tail that is like 18 - 20 carbons long. Inside this phospholipid bilayer it is hydrophobic because that is where the long carbon chains hang, and outside this bilayer is either the surrounding biological media which is mostly composed of water, and the cytosol (inside the cell membrane) which is also composed of many biological molecules dissolved in water.

So the transmembrane protein has to be soluble in the cytosol and the surrounding matrix, and it has to span the phospholipid bilayer which is hydrophobic. Furthermore, the answer is not d) because the cell has to communicate with the surrounding environment through conformational changes in substrate binding and phosphorylation on opposite edges of the integral protein.