The graffiti left an _____ mark on the wall that couldn't be removed.

• A. Index
• B. Indelible
• C. Indicate
• D. Indigenous

Answer: (B)

The key idea here is choosing a word that describes a mark that cannot be erased. Indelible is the best fit because it means permanent or not removable, exactly matching the idea that the graffiti left a mark that couldn’t be removed. In this sentence, mark is a noun and indelible functions as an adjective describing it, giving the sense of a lasting, permanent stain.

The other options don’t fit the meaning or grammar. Index is a noun meaning a sign or list, not something that describes a mark as permanent. Indicate is a verb meaning to point out or show, so it wouldn’t modify a mark in this way. Indigenous means native to a place, which has nothing to do with permanence or removal of a mark.