A．Colombia.
B．Peru.
C．Bolivia.
D．Vietnam.

A．Pay farmers to plant other crops.
B．Forbid farmers to grow coca.
C．Punish those farmers who run drug business.
D．Tell farmers the harmful effect.

A．Because the U.S. government encourages them to do so.
B．Because they are driven by others.
C．Coca is popular in Colombia.
D．Because they can make more money from growing coca.