Let's try to sum up Ringer's arguments:
- Beethoven was forced to look outside of Austria for creative models
- Beethoven was inspired by pianists in London who were connected with Clementi
- The London Pianoforte school was circumscribed and relatively uniform
- The influence of this school was primarily around 1800
In order to undermine Ringer's argument as described in the passage, we're going to need to weaken one of these ideas. Going down the line:
Answer choice (A) tells us that there were creative composers in Austria during the pertinent time period. Ringer's argument relies on assuming that Beethoven had to look outside of Austria, but this statement gives us an alternative: he could have looked towards creative models in his own country. If this statement is true, then Ringer would have to defend the notion that Beethoven had to look all the way to London for inspiration, when he could have much more easily looked closer to home.
Answer choice (B) lines up the time frame of Clementi that Ringer needs and will thus strengthen the argument
Answer choice (C) tells us nothing of the influence of musicians in London, as "Continental musicians" describes musicians on the European mainland; i.e. not London. Ringer's argument does not allege that Beethoven was influenced solely by English musicians, so it is irrelevant to the argument.
Answer choice (D) strengthens Ringer's assumption that the school was relatively uniform
Answer choice (E) does not truly affect any part of Ringer's argument. We do not care why the musicians in this group came to London or if they were local Londoners or foreigners. This
may strengthen the idea that the school was circumscribed, but even that is a stretch.