Which of the Following Is a Sound Argument

Multiple Choice

Which of the following is a sound argument?

A) "If the moon is made of cheese, then Barack Obama is the president of Mexico. The moon is made of cheese. Therefore, Barack Obama is the president of Mexico."
B) "Either Turkey is a country or New York is a country. New York is not a country. So Turkey must be a country."
C) "I have seen millions of black crows. Therefore, all crows must be black".
D) "If the Earth is flat, then John Kerry is president of the United States. The Earth is not flat. Therefore, John Kerry is not president of the United States."