To form the plural of many nouns ending in f or fe, add -s add -es change the f or fe to v and add -s change the f or fe to v and add -es

To form the plural of many nouns ending in f or fe, change the f or fe to v and add -es.

In nouns which ends with F or FE the plural form is different from others. You shoul do one more step. First take the flection, then add V and finally add the plural flection ES.

For example:

Knife > knives

Self > selves

life > lives

Most nouns form their plural by just adding -s to the nouns. For example, cat- cats.

But in the case of nouns ending in F or FE the rule is that the F is changed to VE before adding the -s. Such as the following examples: wife   wives-   wolf  wolves

But there are some exceptions, for example

belief- beliefs/chef- chefs/chief- chiefs/roof - roofs

Nouns ending in -s -ss -ch -sh- x or z form their plurals adding -es to the nouns.  For example, peach-peaches/ fox-foxes

Nouns ending in -o in their singular, form their plurals adding -es

tomato-tomatoes/ potato-potatoes

Nouns ending in -y preceeded by a vowel, an -s is added to the noun, example day-days   but if the nouns ending in  -y and preceeded by a consonant changes the -y into -ies. Example factory- factories

There are also some irregular plurals that do not follow the rules, such as

child-children/ goose-geese

Some nouns keep the same spelling either in the singular and plural form

sheep-sheep/ series- series/ deer- deer/ species-species

d.) gold is the correct answer