1711
After 20 million years or so , the seas started to flood the land again until much of Great Britain was again below the sea , though sea levels frequently changed .
 location: Great Britain
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Great Britain 
Answer:
 location: Great Britain