Question: Which of the following is true about the global growth rate?
A: The global growth rate was four times as high 50 years ago as it is in 2020.
B: The global growth rate was two times as high 50 years ago as it is in 2020.
C: The global growth rate is two times as high as it is in 2020.
D: The global growth rate is four times as high today as it is in 2020.
Please eliminate two incorrect options first, then think it step by step and choose the most proper one option.