Final answer:
The NOT TRUE statement is that persons under the legal driving age may operate recreational vehicles, as typically individuals must meet the legal driving age to operate such vehicles. Recreational vehicles can cross railway tracks, and insurance coverage for an ATV used in water may be excluded by endorsement depending on the policy.
Step-by-step explanation:
The statement that is NOT TRUE among the options provided is: Persons under the legal driving age may operate recreational vehicles. In general, individuals must meet the minimum legal driving age requirement to operate motorized vehicles, including recreational ones, on public lands or roads. While there might be exceptions on private property with the landowner's permission and appropriate safety measures, the statement as presented suggests a general allowance that does not legally stand.
Concerning recreational vehicles crossing railway tracks, they are indeed permitted to do so, provided that they do so at designated crossings and with due caution. As for drivers of recreational vehicles needing to be licensed, while there are scenarios (such as on private property) where a license may not be strictly required, for the most part, drivers on public roads or lands do need to be licensed.
The use of All-Terrain Vehicles (ATVs) in water may impact insurance coverage; this is a nuanced issue and depends on the specific policy. Coverage can be excluded by an endorsement for specific uses of ATVs, such as operating them in water if it's against the insurance policy's terms.