B. Yes, but only when you stop at intersections.
C. Yes, but you must hold the steering wheel with at least one hand.
Any use of a mobile phone, even hands-free, creates a distraction in your vehicle. This video from WA police takes a funny look at distracted driving using Lego.
Having a conversation diverts your attention from the road. It is illegal to use a hand-held phone while you are driving. Even using a hands-free phone is a distraction. However, it is a reality that some people need to use a phone to conduct business in their vehicle - tradespeople travelling between jobs, for example.
If you do take a call on a hands-free mobile phone kit, give yourself more of a buffer to the vehicle in front. If the road needs more priority you can always tell the person you will call them back later.
Hands-free phone kits are available from many retailers. Almost all new cars come with Bluetooth phone integration with the car's audio system, although this won't help you if your phone doesn't support Bluetooth.
Other distractions in your car include: