Final answer:
The passage supports the purpose of informing the reader about Azy's humanlike behavior, especially in how Azy categorizes words, suggesting the cognitive process of classification and the use of analogy.
Step-by-step explanation:
The best explanation of how the passage supports the author's purpose is that the author's purpose is to inform. Shumaker's comments about Azy's mistake in selecting symbols demonstrates a keen observation on how Azy categorizes words, which suggests that the orangutan is exhibiting humanlike behavior through language use. The author does not seem to be instructing readers on how to train orangutans or claiming Azy to be the smartest orangutan, nor does the author criticize the credibility of the orangutan experiment. Instead, Shumaker's intrigue over Azy's mistakes supports the purpose of informing readers about the cognitive processes at play, such as classification and potentially the use of analogy to group objects and actions into categories.