Which of the following statements is accurate with regard to the observation that "income levels in countries hard hit by malaria are 33% lower than in similar countries free of the disease. a. The observation demonstrates that correlations provide excellent indications of causality b. This observation suggests that symptoms from malaria cause patients to lose pay because they miss work c. In order to understand the cause of this observation, scientists should eradicate malaria in ten countries but not in ten other comparable countries in order to experimentally test whether malaria caused the low income levels d. This observation is an example of a correlation and therefore causality cannot be inferred as confidently as if we have results from a manipulated