A physical quantity z depends on four observables a, b, c and d, as z=cd3a2b3. 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 :
a. 12.25%
b. 16.5%
c. 13.5%
d. 14.5%