A man leaves for his office from his house. He walks towards South. After walking a distance of 300 metres, he turns towards West and walks 200 metres. Then he walks 100 metres towards North and further 100 metres towards West. He then turns towards North and walks 200 metres. What is the straight distance in metres between his initial and final positions?

A

300 metres

B

200 metres

C

250 metres

D

400 metres