Which of the following is a light cargo transport aircraft?

The NU-1B Otter is recognized as a light cargo transport aircraft, making it the correct option. This aircraft is designed primarily for utility and transport missions, and it is equipped to carry small loads of cargo or personnel. Its versatility allows it to operate in various environments and conditions, making it suitable for transporting supplies, equipment, and troops, especially in remote and rugged areas.

In contrast, the other aircraft listed serve different primary purposes. The P-3C Orion is primarily a maritime patrol and reconnaissance aircraft, designed for anti-submarine warfare and maritime surveillance. The P-8A Poseidon, which is a more advanced successor to the P-3C, focuses on anti-submarine and anti-surface warfare, as well as intelligence, surveillance, and reconnaissance missions. The T-6A Texan II is primarily a trainer aircraft, used to train military pilots, rather than for cargo transport. Thus, while they all have significant capabilities, the NU-1B Otter stands out as the dedicated light cargo transport among them.