The correct option is D Roger Federer
Roger Federer, a Swiss professional tennis player, won the 2018 men's Singles title in the Australian Open 2018. He successfully defended his title by defeating 6th seeded Marin Cilic of Croatia by 6-2,6-7, 6-3 3-6, 6-1. With this, Federer won his sixth title at the Australian Open equalling the record held by Roy Emerson and Novak Djokovic. The win brought the Swiss to the elite group of Margaret Court, Serena Williams and Steffi Graf, the only players to have won 20 or more Grand Slam singles titles.