Thanks. Could you please give me a reason?
Because when you are referring to a human being, you use who. When referring to an animal or an inanimate object, you use which.
My brother, who is very tall, is a basketball player.
My boss, who is very rich, has a big house.
Your uncle, who has grey hair, has blue eyes.
The cat, which is black and white, has fish for breakfast.
The table, which only has 3 legs, falls over very easily.
The candles, which smell of vanilla, are on the mantelpiece.