Which of the Following Is an Effective and Often-Used Way

Which of the following is an effective and often-used way of judging validity of data from an international market or source?

A) determining how much the data costs
B) checking the consistency of one set of secondary data with other data of known validity
C) examining government seals of approval or authenticity
D) using only U.S.researchers to conduct any research
E) checking the consistency of the data with focus groups