Which of the Following Is True of Intra-Industry Trade

Which of the following is true of intra-industry trade?

A) Intra-industry trade is mostly based on the differences stressed in the Heckscher-Ohlin trade theory.
B) Intra-industry trade is usually discouraged by the government.
C) Intra-industry trade is said to occur when the United States exports Ford automobiles and imports Honda automobiles.
D) Intra-industry trade is said to occur when the United States exports Ford automobiles and imports petroleum.