Four advantages of breast milk

The student - not necessarily a 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.

Um. 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.