안녕하세요, AP English Lang을 수강하고 있는 학생입니다.

Lesson 1 MCQ Reading Question 9에서 a가 틀린 이유는 it was modern research, not former research, that asserted that milk souring was caused by a variety of bacteria 라고 하셨는데요, 아래의 이유에서도 a가 틀릴 수 있는건가요?

Choice a implies that milk souring is not caused by a variety of bacteria because it says that milk souring is mostly caused by Bacillus acidi lactici, "although" former research stated otherwise (that it's caused by a variety of bacteria), when in fact, it is also caused by a variety of bacteria, only that Bacillus acidi lactici is the more common cause. Or is this reasoning inapplicable because choice a is just stating that former research did not take into account of the commoness of Bacillus acidi lactici as the cause in milk souring, but it does admit that it can be caused by other bacteria as well.

감사합니다!