Final Answer:
3.Telnet because Telnet is the optimal utility for testing all 7 OSI layers as it operates at the application layer, allowing comprehensive assessment across the entire networking stack.
Step-by-step explanation:
Testing all 7 OSI layers requires a protocol that can traverse the entire networking stack. Among the options provided, Telnet is the most suitable utility. Unlike Ping, which primarily operates at the network layer (Layer 3) and Trace Route, which traces the route to a destination, Telnet is a versatile tool that can establish a connection to a remote host, allowing testing across multiple layers. Telnet operates at the application layer (Layer 7) and can interact with services at various layers, making it a comprehensive choice for testing the entire OSI model. It encapsulates data from the application layer down to the physical layer, making it an effective tool for assessing end-to-end connectivity and functionality across the entire networking stack. Therefore, Telnet is the utility of choice when the goal is to test all 7 OSI layers comprehensively.