If the speeds are in geometric progression, then the ratio is

Question

The headstock of lathe has 9 speeds with minimum speed of 100 r.p.m. and maximum  speed of 1600 r.p.m . if the speeds are in geometric progression, then the ratio is                 

         (a) 1.06       (b) 1.22        (c) 1.41(d) 1.64