The following sentence has been split into four segments. Identify the segment that contains a grammatical error.
How can someone / walk this farthest / just for / peace of mind?

Correct option is A

Option (a) walk this farthest contains an error.
Explanation: The error lies in the use of "farthest" which is a superlative form typically used to compare more than two items.
In this context, the correct form should be "this far" to indicate the extent of walking without a comparative reference.
Grammatical rule used: Superlative adjectives should be used when comparing three or more entities; for indicating extent without comparison, the adverbial form "far" is appropriate.
Example: "How can someone walk this far just for peace of mind?" is grammatically correct.