Given the task definition and input, reply with output. Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Context: The Three Little Wolves and the Big Bad Pig is a children's picture book written by Eugene Trivizas (Evgenios Trivizas), illustrated by Helen Oxenbury, and first published by Heinemann in 1993.
Question: Who was The Three Little Wolves and the Big Bad Pig illustrated by?
helen oxenbury