Answer:
Electronic flow is true.
Conventional flow was thought to have positive charges flowing from the + terminal to the - terminal. This was before we knew that it is actually the electrons which flow, and the positive charges cannot move out of their atomic nuclei. Now that electrons have been detected, and protons are known to stay within the nucleus unless a nuclear reaction takes place, we know that it is the electrons that flow from the - terminal to the + terminal. This is known as electronic flow.