Some People Believe That Trade Such as the Buying and Selling

Some people believe that trade such as the buying and selling of human kidneys is exploitative because:

A) poor people have less information than wealthy individuals.
B) wealthy individuals choose to buy kidneys from poor people only because they are willing to sell them for less.
C) poor people have little choice but to sell things (such as their own kidneys) which they would really rather keep.
D) these types of risky exchanges happen only in poor countries.