Which of the Following Is Correct with Regard to the Issue

Which of the following is correct with regard to the issue of productivity?

A) A 2011 OECD study showed that Singapore has the world's highest productivity.
B) Countries do not have to worry about their productivity if they are not very involved in global trade.
C) Manufacturing productivity is higher than service productivity.
D) Industries do not differ much in terms of productivity.
E) All of these are correct.