Peter is writing a scientific report about a new car engine a company plans to launch. Which TWO sources are best for him to use in the report?
A. a customer who is eager to try out the new engine
B. a journal article about the impact of engines on car performance
C. an employee of the company who is involved in advertising the new engine
D. an interview with an expert on how car engines function
E. a newspaper article about the company’s different car models