Answer: OPTION C
Explanation: Observation is a data collection method under which the analyst tries to gather the knowledge about the subject data by observing the different phenomena related to the data .
A. Purpose must be disguised as the observations are done for the collection of data and can affect the judgement of observer.
B. A natural setting is necessary or there might be some unfair results in observation.
C. Anonymity is not desired as it could hide some important perspectives of the subject leading to false observations.
D. Memory decay is a factor in considering observation as it can result in improper results.
E. Observation can not be done on quantitative data.