Since you didn't have any extra information about the question I'll be presenting an example from my own textbooks that I've used.
An example of a direct observation is listening to a cricket chirp at night, and counting the number of chirps per minute.
Direct Observation is where the evaulator watches the subject in their usual habitat without disrupting or altering it.
4...........................
Answer:
A. a system that can be affected by the outside environment, by an exchange of matter or energy
Answer:
The first one has the weakest bond
Explanation:
The number of atoms together shows how strong the bonds in the second bond it is 4 bonds, the third is 8 bonds, the 4th one is 4 bonds thus why the first bond is the weakest.