The highest-ranking detectives in the city' s police department are also the most adept at solving crimes. Yet in each of the past ten years, the average success rate for the city' s highest-ranking detectives in solving criminal cases has been no higher than the average success rate for its lowest-ranking detectives. Which one of the following, if true, most helps to resolve the apparent paradox?
A: The police department generally give the criminal cases that it expects to be the easiest to solve to its lowest-ranking detectives.
B: It generally takes at least ten years for a detective to rise from the lowest to the highest ranks of the city's detective force.
C: None of the lowest-ranking detectives in the police department had experience in solving criminal cases prior to joining the police department.
D: The detectives who have the highest success rate in solving criminal cases are those who have worked as detectives the longest.
Choose A, B, C or D as your solution.
A