Answer:
The correct answer is "The head of the phospholipid, which is hydrophilic, helps to control the movement of large hydrophobic molecules, and the tails of the phospholipid, which are hydrophobic, help to control the movement of large hydrophilic molecules".
Step-by-step explanation:
The missing options of the question are
A) "Phospholipids are bulky/large molecules that prevent all molecules from entering/exiting the cell".
B) "The polar tails of the phospholipids provide the barrier between the exterior/interior hydrophilic environments".
C) "Lipids contain high energy bonds, and these bonds help to provide the energy to move molecules across the membrane".
D) "The head of the phospholipid, which is hydrophilic, helps to control the movement of large hydrophobic molecules, and the tails of the phospholipid, which are hydrophobic, help to control the movement of large hydrophilic molecules".
The correct answer is option D). Phospholipids are ambivalent molecules that have an hydrophilic head and an hydrophobic tail. This particular structure not only helps the cell's membrane to isolate the inner components of the cells, but also helps to control the movement of the components within the cells. The movement of large hydrophobic molecules in the cells are controlled by the presence of the hydrophilic heads and viceversa: the movement of large hydrophilic molecules is controlled by the presence of the hydrophobic tails.