Explanation:

Correct Answer is (b).The given sentence implies that the planning of the attack originated from the foreign countries and this has also been proved beyond any doubt. In the given sentence, the error is in the phrase used to denote foreign country or land since foreign soil is used for that purpose and not foreign earth as used in the sentence.
The correct sentence would have been: It has been proved beyond reasonable doubt that the planning of the attack originated from the foreign soil.This makes option B the correct choice among the given options.