It all depends on if you're using traction control and the general grip and power of your car.
In the past when I had the default settings of traction control on 5 and automatic gears, I just used option A) I floored it and let the traction control get me off the line.
With traction control off, just flooring it can make you spin and change direction. So then I use option C of holding the revs below the red line and then add the pressure to the pedal gently.
In some very powerful cars, some people suggest starting in second gear.
There may well be quicker ways, but the above methods consistently give me a good start in online races, when others are spinning and struggling.