The correct option is
C A & B both
Nouns are words that name people, things, places,
animals, etc.
We form the plural noun by adding an 's' to it.
Sometimes, when the noun ends in an 'f', we replace it with 'ves' to form a plural noun.
Option C: 'Scarfs' and 'scarves' are both the plural forms of the noun 'scarf'. Both are acceptable noun forms, where 'scarf' is an older version and 'scarves' is used most commonly today.
Hence option C is correct.
Options A and B both have right answers. But, since we need to choose the option most suitable, C is the correct option and A and B are individually incorrect.
Option D is wrong because 'scarf's' is a singular noun in the possessive case ('s is added to scarf to make it possessive).