Final answer:
The given context does not contain information about an interaction between Ed and Christopher, making it impossible to provide an accurate answer to what Christopher attempts to say before Ed grabs him.
Step-by-step explanation:
The context provided does not include an event where a character named Ed grabs Christopher by the arm, hence it's impossible to determine what Christopher attempts to say in that specific circumstance. To provide an accurate response, the passage that immediately precedes the moment Ed grabs Christopher's arm is required.
Literature comprehension questions often depend on specific textual evidence, so without the correct extract, any attempt to answer the question would be speculative and not factually accurate.
Based on the provided information, it is unclear which specific event or context is being referred to in the question. Therefore, it is not possible to accurately determine what Christopher attempts to say before Ed grabs him by the arm.