What Is the Difference Between Data That Is Collected Anonymously

What is the difference between data that is collected anonymously and data that is collected confidentially?

A) Anonymous research collects participants' names but separates them from the data; confidential research does not collect participants' names.
B) Confidential research collects participants' names but separates them from the data; anonymous research does not collect participants' names.
C) Anonymous research collects sensitive information about participants (e.g., sexual behavior, illegal behavior) ; confidential research collects nonsensitive information about participants.
D) Confidential research collects sensitive information about participants (e.g., sexual behavior, illegal behavior) ; anonymous research collects nonsensitive information about participants.
E) Anonymous research and confidential research are the same thing.