My question is this. If I was to have multiple relays powered from the same rail, but have each one sinking via whatever to respective MCU pins, could I use option B as the single fly-back diode, or must I have it like option A with a diode for each coil? (Obviously with a diode capable of handling the job.)
Please note, my question is about the flyback diode config. Not about MCU current capability or power supply, etc.