Those are (his/her) shorts.
his
Those are (his/her) trousers
her
What are these?
These are trousers
It's (his/her) t-shirt
his
What are these?
These are shorts
Those are (his/her) socks.
his
What's this?
It's a dress
What's this?
It's a T-Shirt
It's (her/his) dress.
her
What are these?
These are socks.