A is wrong because just because left handed people have an advantage painting doesn't necessarily mean there are more left handed painters.
B is wrong because just because left handed people contract diseases more frequently, doesn't necessarily mean that more people with influenza are left handed. For example, left handed people may only make up 2% of the population
C is completely out of the park, there is nothing prove that
D is the best choice. the painters part throws you off a bit, because there is no direct link from painters to influenza but there is a link between left handed people and influenza
E is completely irrelevant