Which of the following best describes a proxy server?

Operates at Layers $3($Network$)$ and $4($Transport$)$ of the OSI model.

Operates at Level $5($Session$)$ of the OSI model.

Operates at Layers $5($Session$)$ and $7($Application$)$ of the OSI model.

Operates at Layer $7($Application$)$ of the OSI model.