What role does the salt bridge play in a voltaic cell? it allows electrons to flow from the anode to the cathode. it allows migration of ions from one half–cell to the other. it contains the electrodes. it creates the oxidation reaction.

The answer is it contains the electrodes. Without the salt scaffold, the arrangement in the anode compartment would turn out to be decidedly charged and the arrangement in the cathode compartment would turn out to be contrarily charged, on account of the charge lopsidedness, the terminal response would rapidly stop. 
It keeps up the stream of electrons from the oxidation half-cell to a decrease half cell, this finishes the circuit.

Solubility would be your answer.