The structure that is located between the nucleocapsid and the envelope is the:

Explanation

In viruses, the matrix protein is a structural protein located between the nucleocapsid and the viral envelope. It helps maintain the shape of the virus, links the envelope to the nucleocapsid, and plays a key role in virus assembly and budding from the host cell. Matrix proteins are especially important in enveloped viruses, such as influenza and HIV, for organizing viral components during the formation of new viral particles.