Identify the segment in the sentence which contains a grammatical error.
You need to sign these important documents by ink.

Correct option is D

Option (d) "by ink" contains an error.
The sentence in question is: "You need to sign these important documents by ink."
· The grammatical error in this sentence is the use of "by ink." The correct phrase should be "in ink."
· When referring to the act of signing with a pen or writing instrument, we use "in ink" to indicate that the signature should be made using ink. "By ink" is not the appropriate preposition in this context.
· So, to correct the sentence, it should be: "You need to sign these important documents in ink."