Question

How is the genitive (possessive) case commonly shown in Modern English nouns? (Mark all that apply.)

adding s' to the singular
adding s' to the plural
adding 's to the singular
adding s to the plural

Answer 1

In Modern English nouns the genitive case is commonly shown by

adding an ´s to the singular, for example:

The neighbor´s cat is sitting on the floor;

adding an s´ to the plural, for example:

Our friends´ cars are parked in front of the restaurant.

Answer 2

Answer: adding 's to the singular.

Examples:
To say you use
The car of Bob Bob's car.
The book of Mary Mary's book