When the manufacturer of Voltage, a major soft drink, changed its secret formula last year, the export earnings of an island in the Indian Ocean began to fall. This island's only export comprises more than half of the world's supply of vanilla beans. Analysts concluded that the original formula of Voltage contained vanilla from beans, but the new formula did not.

Which of the following, if true, would most strengthen the conclusion drawn by the analysts?

(A) The vanilla-bean plantings of a nearby island were beginning to produce crops.
(B) A new process for synthesizing vanilla was under development in a laboratory in the United States.
(C) The island's trade agreement, under which the vanilla beans were exported to the country that manufactures Voltage, had lapsed.
(D) Imports of vanilla beans dropped in countries where Voltage is made.
(E) There were decreases in sales of several widely sold products that were known to contain vanilla.
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Conclusion: Vanilla from beans was one of the ingredients in the original formula but not in the new formula.
We need to focus on the conclusion as that needs to be strengthened.

(A) The vanilla-bean plantings of a nearby island were beginning to produce crops.
Not relevant. We don't need to focus on nearby islands.

(B) A new process for synthesizing vanilla was under development in a laboratory in the United States.
Not relevant. As per the conclusion, vanilla is not being used hence it does not matter how it is being developed. Another indicator is the mention of the USA whereas no such mention is present within the passage.

(C) The island's trade agreement, under which the vanilla beans were exported to the country that manufactures Voltage, had lapsed.
Since the formula has been changed manufacturers don't need vanilla from beans anymore. Additionally, if the trade agreement would have expired it would have meant that the manufacturers were forced to change the formula but from the passage, it is evident that they changed the formula and after that, the exports were impacted and not the other way around. Hence incorrect.

(D) Imports of vanilla beans dropped in countries where Voltage is made.
This complete the logic within the passage. If the export of beans from the island has reduced it logically follow that wherever these beans were being exported, import of those countries should reduce and hence this option is correct.

(E) There were decreases in sales of several widely sold products that were known to contain vanilla.
This takes the whole argument in a different tangent altogether. Not relevant and broadens the scope.

Hence D is the correct answer.

vmkumar, hope this helps with your doubt.
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When the manufacturer of Voltage, a major soft drink, changed its secret formula last year, the export earnings of an island in the Indian Ocean began to fall. This island's only export comprises more than half of the world's supply of vanilla beans. Analysts concluded that the original formula of Voltage contained vanilla from beans, but the new formula did not.

Which of the following, if true, would most strengthen the conclusion drawn by the analysts?

(A) The vanilla-bean plantings of a nearby island were beginning to produce crops.
(B) A new process for synthesizing vanilla was under development in a laboratory in the United States.
(C) The island's trade agreement, under which the vanilla beans were exported to the country that manufactures Voltage, had lapsed.
(D) Imports of vanilla beans dropped in countries where Voltage is made.
(E) There were decreases in sales of several widely sold products that were known to contain vanilla.