David goes camping with walkie-talkies that can operate within a range of 500 feet from each other. David leaves one…

David goes camping with walkie-talkies that can operate within a range of 500 feet from each other. David leaves one walkie talkie with his friend in his tent and then walks 400 feet due south. From that point he walks due west and stops at the maximum range at which his walkie-talkies can still be in range. In which of the following directions can David walk and still be in range of the other walkie talkie? 

I. 200 feet due west 

II. 200 feet due southeast 

III. 300 feet due east 

(a) I only

(b) III only

(c) I and II only 

(d) I and III only 

(e) II and III only