The correct answer is Australia.
Australia is the only host team to win the ICC (50 over) Cricket World Cup. They have won the tournament a record 5 times, in 1975, 1979, 1987, 1999, and 2003.
South Africa has never won the Cricket World Cup, despite hosting the tournament in 2003. They have reached the semi-finals on three occasions, in 1992, 1999, and 2015.
India has won the Cricket World Cup twice, in 1983 and 2011. They were the hosts in 1987, but lost to Australia in the final.
The West Indies won the first two Cricket World Cups, in 1975 and 1979. However, they have not been able to replicate that success since, and have not even reached the semi-finals since 1996.