A container had $27$ ℓ of longan drink. The drink is made up of three $2$-ℓ\textbf{~}bottles of longan syrup and some water. What was the volume of water used to make the drink? 
选项为:A:6ℓ  B:18ℓ  C:21ℓ  D:27ℓ  请回答其中一个选项.