There are only two possible reasons that it would be wrong to engage in an activity that causes pollution: because pollution harms ecosystems, which are valuable in themselves; or, ecosystems aside, because pollution harms human populations. Either way, it would not be wrong to perform mining operations on Mars. Although doing so would pollute Mars, the small human presence needed to run the mining operation would be completely protected from the Martian environment and would suffer no harm. The conclusion drawn above follows logically if which one of the following is assumed? ['There are no ecosystems on Mars.', 'The more complex an ecosystem is, the more valuable it is.', 'Mining creates less pollution than many other human activities.', 'It is technologically feasible to perform mining operations on Mars.']