In a paper published in 2010,
Kate Pickett and Richard Wilkinson found about one in ten people in Japan and Germany suffered some form of mental illness in the year they studied and compared with one in five Britons and Australians and one in four Americans.
1) Kate Pickett and Richard Wilkinson found about one in ten people in Japan and Germany suffered some form of mental illness in the year they studied and compared with
2) Kate Pickett and Richard Wilkinson found about one in ten people in Japan and Germany suffering some form of mental illness in the year they studied, compared to
3) Kate Pickett and Richard Wilkinson found that about one in ten people in Japan and Germany suffered some form of mental illness in the year they studied, but compared with
4) both Kate Pickett as well as Richard Wilkinson found that about one in ten people in Japan and Germany suffered some form of mental illness in the year they studied, compared to
5) Kate Pickett and Richard Wilkinson found that about one in ten people in Japan and Germany suffered some form of mental illness in the year they studied, compared with
First, when we report the results of a study, theses, hypothesis, findings, and the like, it is customary to introduce the effects in a subordinate clause introduced by 'that.'
Einstein's theory proposes that all the cosmic bodies bound by the 'Relativity' theory
His study proves that marine fish does not grow well in fresh water
However, we can also drop the subordinate conjunction 'that; but the structure will then involve an infinitive or a gerund
Einstein's theory proposes all the cosmic bodies to be bound by the 'Relativity' theory
His study proves marine fish not (to grow well/growing well) in fresh water.
That is the reason that we can drop A and B.
Second, when we write a simple sentence containing one IC followed by a modifier, then we should never use a co-ordinate conjunction such as 'and' or 'but.' Else, the sentence will turn unparallel. C is gone.
D is unidiomatic, as Chetan has pointed out, leaving E as the only reasonable choice