Unsupported. We don’t know how difficult it was for Beethoven to compose his music at any point during his life. We’re not told loss of hearing made composing more or less difficult.

Unsupported. Although his later music probably wouldn’t have been as introspective had he not lost his hearing, that doesn’t imply it would have been worse. His music could have gained other positive qualities that would have made up for the loss of the introspective quality.

Unsupported. Although his later music probably wouldn’t have been as introspective had he not lost his hearing, that doesn’t imply anything about the introspection of Beethoven himself. There’s a difference between the person and his music.

Unsupported. We don’t know whether the increased introspective quality in Beethoven’s music came gradually or suddenly. We’re told complete hearing loss gave the music an introspective quality; this doesn’t imply that partial hearing loss lead to a partial introspective quality.

Strongly supported. We’re told that the cause of the introspective quality in his later music was complete hearing loss. This is evidence that if he hadn’t lost his hearing, his music probably wouldn’t have been as introspective.