Explanation
Correct answer: D.
Choice D is the best answer. Ishii and O’Mahony were trying to isolate the pure umami flavor, while Jünger was trying to recreate soy sauce, which has a mix of flavors that includes umami. Accordingly, the broths from Text 1 are not described as having any soy sauce in them—just “shiitake mushrooms and kombu seaweed.” So they probably don’t have as much of the dipeptides described in Text 2, which were found to be a key part of soy sauce’s umami-ness and its saltiness.
Why the other choices are wrong
Choice A
Choice A is incorrect. Neither text supports this. Neither text gets into the diets of people in the United States, nor the diets of people in Japan.
Choice B
Choice B is incorrect. Neither text supports this. Text 2 does talk about the molecular weights of chemical compounds, but there isn’t enough information provided about molecular weights in Text 1 to make an inference about what the scientists in Text 1 would say.
Choice C
Choice C is incorrect. Neither text supports this. Text 1 briefly mentions that soy sauce is “made from fermented soybeans,” but it never claims that fermentation is responsible for its flavor in any way. And Text 2 never mentions fermentation at all.