I'll take answer C for a million dollars, please
Sky News :
Metropolitan Police Commissioner : Well rehearsed and sophisticated emergency plan swining into action. Police want people to stay where they are, do not call emergency services unless a life or death matter. Situation now coming under control
Well I've got to say that if that's it then it has been a rather ineffective attack. I don't think islamic terrorists are yet competing on the level of the IRA, and if they intended to shock britain they have failed.