Select the correct inference of the given passage from "The Cask of Amontillado."

"Against the new masonry I re-erected the old rampart of bones. For the half of a century no mortal has disturbed them. In pace requiescat!"

Question

Select the correct inference of the given passage from "The Cask of Amontillado." 

"Against the new masonry I re-erected the old rampart of bones. For the half of a century no mortal has disturbed them. In pace requiescat!"

anonymous · Answer

The narrator has plotted his revenge in secret.  (I think this is the answer)