The Bobbsey Twins

The original Bobbsey Twins books may have been published a few generations before my time, but the series enjoyed a resurgence of popularity during my childhood. I loved the mystery-solving twins, who resided on my bookshelf alongside the Boxcar Children, Nancy Drew, and the Hardy Boys.

How well do you know the Bobbsey twins—all four of them?

Note: The image used for a particular question is not necessarily from the book mentioned in the question/answers.