Feinberg states the Fair Opportunity Requirement as follows. "Differences in a given respect are relevant for the aims of distributive justice, only if they are differences for which their possessors can be held responsible; properties can be the grounds of just discrimination between persons only if those persons had a fair opportunity to acquire or avoid them." (C 353) Which of the following principles (if any) meet the Fair Opportunity Requirement according to Feinberg? a. Principle of Strict Equality b. Principle of Need c. Principle of Merit (skill) d. Principle of Merit (virtue) e. Principle of Achievement f. Principle of Contribution g. Principle of Effort