A current passes through a wire of non-uniform cross section. Which of the following quantities are independent of the cross-section?

The current trough a conductor is independent of the area of cross-section. It will be same through out the length of the conductor. 

The charge crossing in a given time interval is nothing but current and it is independent of area of cross-section.

Current density and Drift speed are related with area of cross section and are inversely proportional to it. 

Free-electron density is again independent of the area.