Concept:The floor function [tanx] stays constant on intervals where tanx lies between consecutive integers.Explanation:On [0,3π], tanx increases from 0 to 3.Since 3≈1.732, the value of tanx lies between 0 and 2.Hence [tanx] can only be 0 or 1.For 0≤x<4π, we have tanx<1, so [tanx]=0.For 4π≤x≤3π, we have 1≤tanx<2, so [tanx]=1.Thus the integral splits as:∫0π/3[tanx]dx=∫0π/40dx+∫π/4π/31dx=(3π−4π)=12π.So the value of the integral is 12π, which matches option A.Answer:12π (Option A)