In this newspaper article on sentence phrasing in a primary school (Grade 3) science examination, this question came up:
WHAT is the difference between a bird and a lion? If your answer is "the bird has feathers but the lion does not", your answer would have been marked as incorrect for the Primary 3 science paper.
The correct answer prescribed by the teacher was: "The bird has feathers but the lion does not have feathers."
Is the teacher wrong to state that the sentence must contain the redundant "have feathers"? If so, what grammatical/stylistic rule does this redundancy violate, and if not, why not?