Answer:
The answer to your question is: D.
Explanation:
Distance refers to the amount of space between two points, it is a scalar quantity.
Displacement refers to the space between two points, measure from the minimum path linking them, it is a vector quantity.
I'm not agree with these answers, because the total distance  is approximately 500km.
A) The distance traveled is 300 km. Â This answer is not correct.
B) Distance is 300 km and displacement is 0 km. Â This answer is not correct because the displacement is also 500 km.
C) Distance is 300 km/hour and displacement is 300 km.
300 km/h is a measure of speed not of distance, this option is wrong.
D) Both distance traveled and displacement are 300 km. I think this is the correct answer because distance and displacement measure the same. but I think both measure 500 km.