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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Deepak singh 1
X1 is collection of rationals of (0,1) and rational are countable so X1 is countable . And X2 is subset of X1 which is countable , so X2 is also countable . [0,1]/ X1 and [0,1]/X2 is uncountable . because [0,1] is uncountable. So option a and b are correct.