The first and third choices could both do it, but the first choice makes a much better, clear demonstration.
I didn't want to type all of this, so instead I showed proof and gave you the answer.
The direction of its displacement wil be
c.northeast
In fact, the dog walks north for 10 meters and east for another 10 meters. The path of the dog can be represented with two vectors, A pointing north (of magnitude 10 meters) and B pointing east (of magnitude 10 meters). The direction of the resultant vector (due to east) will be given by


and the direction will be north-east.
Mass of a sample of gas doesn't change, no matter what happens to its pressure, volume, or temperature.
Answer:
D
Explanation:
The greater the mass, the greater the inertia, and vice versa.
Remark: This means that a more massive object has a greater tendency to resist a change in its state of rest or motion.