Option D.) 1/5 + 1/20 + 1/80 + 1/320 is correct
Geometric progression is kind of progression that the ratio to the adjacent values always same.
ratio in every option is not same except option D. 1/5 + 1/20 + 1/80 + 1/320
i.e. (1/5)/(1/20) = (1/80)/(1/20)
Thus the Option D.) 1/5 + 1/20 + 1/80 + 1/320 is correct
Learn more about geometric progression here:
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