Scientists use many different methods of investigation. When possible, scientists want to actually experiment or observe an event. Which method is useful when developing a scientific explanation for an event that cannot be studied directly? A. Conduct a field survey of bird populations in an area. B. Observe the effect of various fertilizers on corn crop yields. C. Use a computer model to study how the ocean liner Titanic sank. D. Use a wind tunnel to measure air drag on various types of automobiles.