Answer:
C. H2O diffuses in.
Step-by-step explanation:
The phospholipids-made synthetic vesicle in this case will act like a semi-permeable membrane while the solution in the interior lumen will be hypertonic to the surrounding pure water.
Hence, water molecules will diffuse into the lumen through the semi-permeable membrane because of the osmotic gradient that exist between the internal and the surrounding solution of the vesicle.