Correct option (b) 163 cm
Explanation:
Pillar X: In one chance, A climbs on X by 6 cm but slips down 1 cm.
Hence, in one chance A climbs 6 – 1 = 5 cm.
Height attained after 39 chances = 39 × 5 = 195 cm
Thereafter in the 40th and last chance it will climb 6cm to reach the top.
So, height of pillar X = 195 + 6 = 201 cm
Pillar Y: In one chance, B climbs on Y by 7cm but slips down 3cm.
Hence, in one chance B climbs 7 – 3 = 4 cm.
Height attained after 39 chances = 39 × 4 = 156 cm
Thereafter in the 40th and last chance it will climb 7 cm to reach the top.
So, height of pillar Y = 156 + 7 = 163 cm
Pillar Z: In one chance, C climbs on Z by 6.5 cm but slips down 2 cm.
Hence, in one chance C climbs 6.5 – 2 = 4.5 cm.
Height attained after 39 chances = 39 × 4.5 = 175.5 cm
Thereafter in the 40th and last chance it will climb 6.5 cm to reach the top.
So, height of pillar Z = 175.5 + 6.5 = 182 cm
So, height of the shortest pillar (i.e. pillar Y) = 163 cm