HERE'S THE ANSWER

May 18, 2020   photos  

Of course stranded wire because the current will not be inside the wire but it will be in the cover of each thin wire in stranded wire so this kind will be better. 
It is the multiple stranded cable that carries high AC currents due to "skin effect".
Now for Dc currents it is still the multiple stranded cable since now the crossection area of the core is utilized for this case.
The multiple strands are also advantageous in the way that in case of heating in a cable due to flow of high currents, there will be expansion with in the strands and hence cooling up the cable. Finally, in case of low freq, of course solid wire can take higher current. But in case of high frequency like RF, solid wire carries less current due to skin effect.