Answer:
-Selective permeable nature.
Step-by-step explanation:
Plasma membrane allow transfer of certain molecules across it due to its selectively permeable nature. Due to this, only certain molecules or substances (which are are allowed to enter or exit the cells.
Selective permeable nature of plasma membrane is important for cells as it helps in maintaining cellular health, balanced level of fluids and electrolytes, and homeostasis.
Thus, the feature of a plasma membrane that describes whether substances can cross the membrane or not is its selective permeable nature.