<u>The key difference in six and seven-continent model is that the former is taught in Europe, Japan, and Russia while the latter model is preached in the United States, Asia, United Kingdom, and Australia</u>. In the six-continent model, South America and North America are merged into one section named 'America' while the seven-continent model denotes them separately. Thus, <u>option A</u> is the correct answer.
Explanation: The validity of a hypothesis needs to be proven for the research to be considered correct. All research must have good parameters, both valid and reliable, to be considered as real and serious research.
