Final answer:
The total displacement from the multiple movements is found by subtracting the northward vectors from the southward vectors, resulting in a total displacement of 2 km south, corresponding to option D. is the correct answer.
Step-by-step explanation:
To answer the student's question regarding the total displacement resulting from a series of movements, we will use the principles of vector addition in physics.
The four displacements given are 4 km south, 2 km north, 5 km south, and 5 km north. Since south and north are opposite directions, we can subtract the values moving in these different directions.
Firstly, we combine the displacements heading south: 4 km south + 5 km south = 9 km south. Next, we sum the displacements heading north: 2 km north + 5 km north = 7 km north. Now, we find the total displacement by subtracting the northward displacement from the southward displacement: 9 km south - 7 km north = 2 km south.
Therefore, the total displacement is 2 km south, which corresponds to option D.