How to find true velocity here? Isn't it should be just omega cross radius?

Question: 9/60 An xyz coordinate system is rotating with respect to another XYZ coordinate system having the same origin and assumed to be fixed in space [ie., tis an inerial system] The angular velocity of the xyz system relative to the XYZ system is given by o-2ti-tj-(21+4k wihere t is the time. The position vector of a particle at time t as observed in the xyz system is given by r-(1 -6fj- 4tk. Find the true velocity at time t= 1. (A) 2i-6)+12k (B) 34i+2j-2k (C) 2i-6j-12 (D) 34i-2j+2k