We are supposed to counter the claim with our assumption:-
(A) Foreign companies did benefit when Country X lowered tariff barriers, but consumers in Country X benefited just as much.
--> Though it is a possibility, but it doesn't counter the claim that Foreign companies induced the change.
(B) In the period since tariff barriers were lowered, price competition among importers has severely limited importers’ profits from selling foreign companies’ products in Country X.
-->It talks about profit of importers not of foreign companies. Low tariff doesn't necessarily means high imports
(C) It was impossible to predict how Country X’s economic reforms, which included lowering tariff barriers, would affect the economy in the short term.
-->out of scope
(D) Many of the foreign companies that benefited from Country X’s lowering tariff barriers compete fiercely among themselves both in Country X and in other markets.
--> changes doesn't affect competition.
(E) Although foreign companies benefited when Country X lowered tariff barriers, there is no other evidence that these foreign companies induced the change.
-->Here, it is clearly stated that there is no evidence that foreign companies induced the change, while accepting that companies gained from the change.