If a namespace is present in a library then which of the following is the correct way to use the elements of the namespace?

• Add Reference of the namespace. Use the elements of the namespace.
• Add Reference of the namespace. Import the namespace. Use the elements of the namespace.
• Import the namespace. Use the elements of the namespace.
• Copy the library in the same directory as the project that is trying to use it. Use the elements of the namespace.
• Install the namespace in Global Assembly Cache. Use the elements of the namespace.