Select the most appropriate option that can substitute the highlighted segment in the given sentence to improve it. If no improvement is required, select ‘No improvement required’.
It seems that these walls have not been painted since years.

Correct option is C

The correct substitution of the highlighted words is (c) have not been painted for years.
· The correct phrase is "for years" instead of "since years." The preposition "for" is used to indicate a period of time when discussing the duration of an action. "Since" is used to indicate a starting point in time but would not be appropriate in this context.
· Grammatical rule used: When referring to a period of time during which something has been happening, "for" is used, followed by the amount of time. "Since" is used with a specific point in time, not a duration.
· Example: "She has not visited her hometown for years." This correctly uses "for years" to indicate the duration of time.