Which Statement Is Not True About Why It Is Difficult

Which statement is not true about why it is difficult to conduct field experiments in the international arena?

A) In many countries,the TV stations are owned and operated by the government with severe restrictions on television advertising.This makes field experiments manipulating advertising levels extremely difficult.
B) The lack of major supermarkets in the Baltic states makes it difficult to conduct field experiments to determine the effect of in-store promotions on the sales of products.
C) Even when basic infrastructures such as roads,transportation,and warehouse facilities are adequate,they do not help in achieving desired levels of distribution.
D) Even when experiments are designed,it is difficult to control for the time order of occurrence of variables and the absence of other possible causal factors,two of the necessary conditions for causality.