We Often Hear of the Third World (Although It Is

We often hear of the Third World (although it is a contested term) . But what is the Second World?

A) The Western hemisphere, with particular reference to the United States (i.e., the term is interchangeable with the 'new' world) .
B) The Soviet Union and its allies.
C) Eastern Asia (particularly Japan and China) .
D) All of the above depending on context.