6. (4.48} German cell phone study: The contingency table shows results from the German study about whether there was an association between mobile phone use and eye cancer (Stang et al., 2001). Eye Cancer and Use of Mobile Phones Controls 46 No 102 429 Total ' 118 t 475 a. The study was \"retrospective.\" Explain what this means. b. Explain what is meant by \"cases\" and \"controls\" in the heading of the table. c. What proportion had used mobile phones, of those in the study who (i) had eye cancer, (ii) did not have eye cancer