Many workers who handled substance T in factories became seriously ill years later. We now know T caused at least some of their illnesses. Earlier ignorance of this connection does not absolve T' s manufacturer of all responsibility. For had it investigated the safety of T before allowing workers to be exposed to it, many of their illnesses would have been prevented. Which one of the following principles most helps to justify the conclusion above? ['Manufacturers should be held responsible for the consequences of any of their actions that harm innocent people if those consequences were preventable.', 'Manufacturers have an obligation to inform workers of health risks of which they are aware.', 'Employees who are harmed by substances they handle on the job should be compensated for medical costs they incur as a result.', 'Manufacturers should be held responsible only for the preventable consequences of their actions.']