The correct option is D Switzerland
Switzerland won the 30th edition of the Hopman Cup tournament 2018 at the Perth Arena in Perth, Australia. It was their 3rd third Hopman Cup title as Roger Federer and Belinda Bencic beat Germany's Alexander Zverev and Angelique Kerber 4-3 (3), 4-2 in the deciding mixed doubles, to secure a 2-1 victory in Perth. It was Federer's second Hopman Cup triumph after victory in 2001 alongside Martina Hingis.