TRANSACTION.....is it like??

[ziyauddinmomin1@gmail.com]

On a crypto exchange, I transferred 1 ether from my account with let's say wallet A to my friend's wallet B. When I searched for my friend's wallet B on etherscan.io to see the transaction, the sender address belonged to crypto exchange's wallet C and not my wallet A. Why do the exchanges do not make the transaction directly from my wallet A to wallet B?