Final answer:
Without direct textual evidence linking the character to the incident of falling into the river, we infer that 'White' could be associated with the rose-colored pyjamas, thus potentially placing White at the scene.
Step-by-step explanation:
The question seems to be from a reading comprehension exercise based on a passage from literature. The correct answer depends on the context provided in the text. From the excerpts given, neither Charlie, Morris, Johnson, nor White are directly mentioned as having tumbled into the river.
However, the mention of 'pyjamas' in the second excerpt suggests that the character involved was likely wearing them. If we associate 'pyjamas' with one of the options given, 'White' could be a logical answer if we infer 'rose-colored pyjamas' pertains to 'White' being a surname rather than the color of the clothing, seeing as the character is mentioned as wearing a fur coat and riding boots, which could imply a subsequent change of attire.