This is a suggestion for improving readability of this problem.
(It is NOT a fix of any bug.)

Enlarge figures
 a) large view of candidate graphs
 b) thumbnails of candidate graphs
 c) graph of correct answer in solution
 d) graph of original function
Merge branch 'master' of github.com:openwebwork/webwork-open-problem-library
Zap bogus stuff appended to problem code.
Merge pull request #61 from Dick-Lane/master

Both parts look like improvements.