Answer:
C. The summary is weak because it only mentions one supporting detail and does not cover the main point of the passage.
Step-by-step explanation:
The above one-line summary is actually weak because it actually mentions just one supporting detail of the passage. It does not cover the main idea of the passage. The one line summary doesn't really give enough idea about the passage which makes the reader to find it difficult to grasp the main idea of the passage if the reader was to go with just the summary. This makes the summary weak.
Therefore, Option C is the correct answer.