Read the following advertisement and mark the letter A, B, C, or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 1 to 6.
During the 1960s and '70s, industrialised countries suffered a(n) ______(1), and violent crimes such as muggings increased at an alarming rate. What is more, it was expected to ______(2) worse. Only it didn't. Instead, it got much, much better. In the 1990s, crime started to fall dramatically, and today it is down by almost 50% across the industrialised world and continues to fall. Triumphant politicians will assert that their policies have cut crime. Actually______(3) of the country's policies, the trend does coincide ______(4) the use and subsequent prohibition of tetraethyl lead in petrol, ______(5) for years as a cause of aggressive behaviour. Therefore, countries that still use leaded petrol are being urged to stop ______(6) it to help improve health and crime prevention.