If, as Emanuel et al. argue, it is exploitative not to provide post-trial benefits in studies that do not result in the identification of beneficial interventions, why should this obligation be limited to research in developing countries? Are there certain features about developing country research that justify imposing a greater obligation to provide post-trial benefits than in studies conducted in wealthier countries?  Alternatively, should researchers in all countries be expected to provide post-trial benefits to study participants?Explain