This isn't my homework. This came up during a friendly debate last night with my mom.
What would be the correct use of the apostrophe and/or plural in the sentence One of my friend(s) house(s) is on sale. in each of the following cases?
My guesses are in bold, but do correct me if of them are any are incorrect.
(a) I have exactly one friend, and he has exactly one house which is on sale.
One of my friends' house is on sale.
(b) I have many friends and one of them is selling his only house.
One of my friends' house is on sale.
(c) I have exactly one friend and he is selling one of his many houses.
One of my friends' houses is on sale.
(d) I have many friends and one of them is selling one his many houses.
One of my friends' houses is on sale.
I think the form One of my friend's... will be incorrect in all cases, unless the noun cannot be realized in plural form, such as in One of my mother's friends is a dentist. Is this right?