Number = countable things (people, products)
Amount = non-countable things (usually describes the extent of things)
In this question, 'irrigation systems' can be counted so we want 'number.' Eliminate (A) and (E). 'Numbers of' is unidiomatic so eliminate (C).
Expensive refers to the price of an actual product. You cannot, however, have a more expensive price.
Higher relates to how much something is. Therefore, we use higher to modify 'price.' Eliminate (D).
That leaves us with (C) as the answer.
1. According to the Federal Trade Commission, the recent increase in the amount of irrigation systems sold by
foreign conglomerates in the United States has resulted in more expensive prices for the American consumer.
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amount of irrigation systems sold by foreign conglomerates in the United States has resulted in more expensive
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number of irrigation systems sold by foreign conglomerates in the United States has resulted in
higher ANSWER
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numbers of irrigation systems sold by foreign conglomerates in the United States has resulted in higher
• number of irrigation systems sold by foreign conglomerates in the United States has resulted in more
expensive•
amount of irrigation systems sold by foreign conglomerates in the United States has resulted in higher
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