Which Statement Reflects a Pervasive Finding of Porter's Study

Which statement reflects a pervasive finding of Porter's study?

A) Successful industries within a country tend to be grouped into clusters of related industries.
B) Trade increases the specialization of production within an industry.
C) The pattern of trade we observe in the world economy may be the result of first-mover advantages.
D) Purchasing power parity of a country determines its demand conditions.
E) Differences in technology may lead to differences in productivity, which in turn, drives international trade patterns.