Let's assume that user has a wallet with 3 bitcoin addresses: A, B, C.
The user received 1 BTC to address A, 1 BTC on address B, 1 BTC on address C.
Now the user wants to send 3 BTC to another user. How would he do it? What about miner fee, will it be more than in case of sending from one address to another? Please help me understand that question.