During the clinton administration, why did the u. s. stiffen its economic sanctions against cuba?

The correct answer is C) Cuba had been guilty of shooting down two civilian planes.  

During the Clinton administration, the U.S. stiffed its economic sanctions against Cuba because Cuba had been guilty of shooting down two civilian planes.  

President Bill Clinton immediately responded to the Cuban shooting down of two United States airplanes on March 12, 1996. He signed into law the Cuban Liberty and Democratic Solidarity Act, best known as Helms-Burton. The Act stiffed the United States economic embargo in Cuba as a consequence of Cuba’s violation of international law-

 The other options of the question were, a) Castro decided to accept Russia Missiles, b) Cuba refused to trade with the U.S., and d) Castro refused to hand over American journalists he held.