Given below are four jumbled sentences. Pick the option that gives their correct order. 
A. Some used cars may have been involved in accidents or salvaged and rebuilt.
B. Before buying a used car it’s important to know everything there is to know about it.
C. If the car engine is clean, it’s a good sign, but still ask for a test drive. 
D. It is therefore very important to examine the car’s engine for any fluid leaks.