The correct option is D 165
We first need to calculate HCF of the dimensions of the floor.
8m70cm=870cm and 6m38cm=638cm
Finding HCF of 870;638, we have
Prime Factorisation of 870=2×3×5×29
We then choose each common prime number with the least power and multiply them to get the HCF.
So the dimensions of each square till be 58cm
Now, least number of square tiles required =AreaofthefloorAreaofeachtile=870×63858×58=165