Answer:
82.1 km
Explanation:
We need to resolve each displacement along two perpendicular directions: the east-west direction (let's label it with x) and the north-south direction (y). Resolving each vector:

Vector B is 48 km south, so:

Finally, vector C:

Now we add the components along each direction:

So, the resultant (which is the distance in a straight line between the starting point and the final point of the motion) is

This question is asking you to determine if individual atoms or systems, or both have these types of energy. A system would be "all the molecules or atoms" whereas an individual atom is "each of the molecules or atoms."
Answers:
A. All the molecules or atoms in motion have kinetic energy.
B. Each molecule or atom in motion has kinetic energy.
D. All the molecules or atoms in motion have thermal energy.
The only incorrect answer is C because individual atoms don't have thermal energy, only when they interact with other atoms. Still, atoms do have kinetic energy, which has the potential to turn into heat energy in these interactions.
Hope this helps!