Approximately how many years did Britain remain separate from the Roman Empire after Julius Caesar's initial invasion?

Julius Caesar's initial foray into Britain in 55 BC was more of a reconnaissance mission than a full-scale invasion. He landed with his legions, explored the territory, and then promptly returned to Gaul (modern-day France). This wasn't the start of Roman rule. It wasn't until nearly a century later, in 43 AD, under the Emperor Claudius, that the Romans launched a proper, sustained invasion and began the systematic conquest and occupation of Britain. So, while Caesar certainly made a splash, it took almost a hundred years for the Romans to actually establish their presence and begin their long-term rule. That's why 100 years is the right answer. The other options are too long, because the Romans came back within a century to actually stay.