Answer:
Phospholipase refers to an enzyme that cleaves the phosphate group from the phospholipids. In the given case, the phosphate group of phospholipid A is projecting towards the external part and the phosphate group of phospholipid B is present within the cell.
As the enzyme is impermeable to the membrane, it will not possess the tendency to cut the phosphate from the phospholipid B. That is why it will only possess the tendency to cleave the phosphate group from phospholipid A and not from phospholipid B.