Final answer:
In a wet type of voltaic cell, the electrolyte is an acidic liquid which is involved in conducting ions between electrodes to facilitate the electrochemical reaction.
Step-by-step explanation:
In a wet type of voltaic cell, an electrolyte refers to an acidic liquid or any other conductive solution that allows ions to move between the electrodes. It is part of the electrochemical reaction that produces electricity. Specifically, in the context of a wet cell, the electrolyte is not a bridge made of salt, which is actually called a salt bridge, nor is it a copper strip, which serves as an electrode. It is also not a spontaneous flow of electrons; that's the electricity generated by the cell's operation. Therefore, the correct answer is c, An acidic liquid.