Final answer:
The Neptune Company likely developed a small inflatable boat for use in NASA's proposed missions to Titan's lakes, based on the context of studies involving inflatables and their behaviors in atmospheres.
Step-by-step explanation:
The question seems to be related to the Physics of gases and buoyancy, particularly as it pertains to objects like hot air balloons and other inflatables that operate within an atmosphere. Based on the reference information provided, Neptune Company has developed a small inflatable, which fits best with the description of a boat that could potentially be used in NASA's future proposed missions, such as one 'floating in one of the Titan lakes.' It's important to note that hot air balloons work because heated gases expand, creating a lower density inside the balloon compared to the cooler atmosphere outside. This difference in density provides an upward buoyant force that allows the balloon to rise.