Step 1: Understanding the Difference Between 'Further' and 'Farther':
"Further" and "farther" are both used to talk about distance, but "further" is generally used in a more abstract sense or to describe figurative distance (e.g., further discussion). "Farther" refers specifically to physical distance.
Step 2: Analyzing the Options:
- Further: The correct option because "further" is used in this sentence to express something that is more abstract, like additional information.
- Neither: This is incorrect because it contradicts the context of the sentence. "Neither" is used in negative constructions, which is not applicable here.
- Farther: This refers to physical distance, which doesn't fit the context of the sentence.
- Either: This is incorrect because "either" refers to one of two possibilities and is not suitable in this context.
Step 3: Conclusion:
The correct word to complete the sentence is further.