What is required to legally transport a firearm in a vehicle in Nebraska?

In Nebraska, it is legally required to transport a firearm in a vehicle unloaded and locked up. Option B and D are incorrect because they both involve having the firearm loaded or visible, which could pose a safety risk. Option C is also incorrect because there are specific requirements in place for transporting a firearm. Therefore, the safest and legally required method of transporting a firearm in a vehicle in Nebraska is to have it unloaded and locked up.