I'm not entirely sure but I'll go with B.
Hope I could help!
The answer is false. The physical properties of a substance can be observed at any time.
Senators are required to work on two standing committees during their term.
Answer:
The student on the left was chosen as the system to be analyzed.
Explanation:
In the example titled “Colliding Students” in the textbook, the student on the left was chosen as the system to be analyzed; while the surroundings was chosen as the Earth, the ground, the air, and the second student who happened to collide with the student on the left.