In Which of the Following Situations Would Written Informed Consent

Multiple Choice

In which of the following situations would written informed consent not necessarily be required?

A) An observational study that measures walking speed of people entering and exiting buildings
B) An anonymous study that measures the relationship between time spent grocery shopping and money spent on groceries
C) A confidential study examining income level and voting behavior
D) Neither a nor b need written informed consent
E) None of the studies above would require written informed consent