Which plural is not formed correctly / a lamp = lamps b crutch=crutches c eaves = eaves d roof = rooves

The plural form of a noun indicates that there is more than one one or subject may it be a place, person, event, animal or an idea. In giving the plural form of the noun, adding s, es, or ies at the end of the noun is usually practiced. In the question above, it is only in letter d. roof = rooves that does form its plural form correctly. The correct plural form of the word roof in the standard English is roofs.