A physical quantity `z` depends on four observables `a , b, c and d` , as `z=(a^2b^(2'/'3))/(sqrtc d^3)` The percentages of error in the measurement of `a, b, c and d` are `2%, 1.5%, 4% and 2.5%` respectively. The percentage of error in `z` is
Options:
(a) 13.5%
(b) 16.5%
(c) 14.5%
(d) 12.25%