What Makes a Semipermeable Membrane Selective for One Chemical Species

Multiple Choice

What makes a semipermeable membrane selective for one chemical species but not another?

A) The pores in the membrane select by size,they are big enough for water only.
B) The material is hydrophilic and therefore only allows water through.
C) The material is hydrophobic and therefore only allows water through.
D) The material chemically reacts with everything but water.
E) none of the above