The not necessarily well-prepared student sat in his life science
classroom staring at a question on the final exam paper. The question
directed: "Give four advantages of breast milk."  What to write? He
sighed, and began to scribble whatever came into his head, hoping for
the best:

1. No need to boil.
2. Cats can't steal it.
3. Available whenever necessary.

So far so good - maybe. But the exam demanded a four-part answer. 
Again, what to write?  Once more, he sighed. He frowned. He scowled,
then sighed again. But suddenly, he brightened. He grabbed his pen,
and triumphantly, he scribbled his definitive answer:

4. Available in attractive containers.