Which Statement About Observation as a Means of Assessment Is

Which statement about observation as a means of assessment is true?

A) Unlike more formal assessments, observation does not provide detailed information about behavior.
B) Observation can be unobtrusive and does not interfere with a child's ongoing behavior.
C) Observation is a relatively ineffective method of assessment because it is subjective.
D) Observation is most useful for measuring children's learning in terms of milestones or individual facts.