Question

Explanation about the relative clauses who whose that .

Answer 1

We use "whom" for people.
Example:
Chris has two sisters. Both of them smoke. - Chris has two sisters, both of whom smoke.

We use "whose" for possesion.
Example:
Tom is a writer. All of his books are popular. - Tom is a writer, all of whose books are popular.

That - subject or object pronoun for people, animals and things in defining relative clauses (who or which are also possible).
Example:
I don’t like the table that stands in the kitchen.