Which of the Following Characterized Crowley Et Al

Which of the following characterized Crowley et al.'s (2001) observational study in a science museum?

A) they used participant observation rather than naturalistic observation (because the parents were involved
B) unlike most naturalistic observation studies, they were able to obtain informed consent
C) because they used videotape, they did not need to determine interobserver reliability
D) they explained their results (parents explaining science more to boys than girls) by simply pointing out that the boys asked more questions than the girls did