The best answer choice that describes the cell membrane's composition and arrangement is Phospholipid bilayer.
The cell membrane is primarily composed of phospholipids, which arrange themselves in a bilayer format. This structure not only provides flexibility and fluidity to the membrane but also creates a barrier that separates the interior of the cell from the outside environment. Additionally, the phospholipids have hydrophobic (water-repelling) tails and hydrophilic (water-attracting) heads, contributing to the membrane's functionality.