It's not a legal requirement that one should answer a mobile phone call immediately. In fact it's not a legal requirement that one should answer a mobile phone call at all.

If it rings while you're driving - ignore the f***ing thing, let the call go to voicemail, listen to it once the driving's finished and call the caller back if necessary.

It's not Rocket Science, is it? It's that old-fashioned thing called 'Common Sense'.