Microphone

[Mathy]

Hello guys

I've bought a radio with built in Bluetooth. And now I'm asking myself what the best position would be for the microphone:

a) on the A-pillar, next to the sun visor
b) in the middle, near the rear view mirror
c) after I install the police panel, somewhere on the panel

What do you guys think?

Sincerely

Mathy