Final answer:
Molecule STN, being planar and hydrophobic, can enter the cell via passive transport, specifically diffusion directly through the membrane, due to its ability to interact with the hydrophobic inner part of the cell membrane.
Step-by-step explanation:
If molecule STN exhibits sufficient planarity and hydrophobicity, it will likely enter the cell by diffusion directly through the membrane. This process falls under passive transport, where substances move from an area of higher concentration to an area of lower concentration without the need for cellular energy. Hydrophobic molecules can often cross the phospholipid bilayer of the cell membrane because they are soluble in the hydrophobic lipid tails that make up the interior of the membrane.