In traditional naturalistic observation, the subject or subjects being studied
a.
will have to sign a waiver to authorize the observation
b.
may be unaware that observation is being conducted
c.
provide detailed explanations of their mental processes
d.
are supposed to change their behavior due to the observation

B. may be unaware that observation is being conducted.

Explanation:

In traditional naturalistic observation, the subject being studied may be unaware that observation is being conducted. This is the case because the scholar studying the subject wants the subject's behaviour to be as natural as possible. However, in modern times, this is often considered to be a violation of the subject's privacy, and full disclosure is now encouraged.