Which of the following aircraft is primarily used for anti-submarine warfare (ASW) and intelligence, surveillance, and reconnaissance (ISR)?

The P-8 Poseidon is specifically designed for anti-submarine warfare (ASW) and intelligence, surveillance, and reconnaissance (ISR) missions. It is a military aircraft that has advanced sensors, weapons systems, and a range of operational capabilities tailored for detecting and engaging submarines, as well as gathering and analyzing intelligence for various maritime operations.

The design of the P-8 allows it to operate effectively in maritime environments, utilizing sonobuoys, advanced radar, and other surveillance technologies to track underwater threats. This makes it a vital asset for fleet commanders who need to maintain maritime security and monitor the activities of potential adversaries in maritime domains.

Other aircraft mentioned, such as the F-18 Hornet, are primarily designed for multi-role fighter missions and air superiority, while the EA-18G Growler focuses on electronic warfare capabilities. The CVN Nimitz refers to a class of aircraft carrier, which, while crucial for naval operations, does not engage in ASW or ISR itself as an aircraft does. The P-8's specialized role distinguishes it as the correct choice in the context of anti-submarine warfare and intelligence operations.