Answer:
Please take a look to the explication below.
Step-by-step explanation:
The inventor who filed the patent application for the widget in December 2017 would receive the patent protection. As the invention is novel and not obvious, the inventors are eligible for patent protection. US had moved from first-to-invent to first-to-file system after the America invents Act in 2011 and hence patents are awarded to the inventor who first files for patent protection.
Before the law, it was awarded to the person who first invented the invention even if they did not file for patent protection. But now it goes to the person who first files the invention and hence the inventor who first invented but filed in March 2018 is not entitled for the patent.