Why Are Black Markets for Human Organs Less Efficient Than

Why are black markets for human organs less efficient than free markets?

A) Prices are lower in black markets than in free markets.
B) Traders are discreet in free markets.
C) There are a more traders in the black market compared to the free markets.
D) Buyers cannot meet openly with the sellers in black market as they can in free markets.
E) There is a steady supply of human organs in the free market while the supply in black market is unpredictable.