Biology test

Students in an advanced Biology class were taking their mid-term exam. The last question was "Name seven advantages of Mother's Milk,' worth 70 points or none at all." One student, in particular, was hard put to think of seven advantages. He wrote: 1.) It is perfect formula for the child. 2.) It provides immunity against several diseases. 3.) It is always the right temperature. 4.) It is inexpensive. 5.) It bonds the child to mother, and vice versa. 6.) It is always available as needed. And then, the student was stuck. Finally, in desperation, just before the bell rang indicating the end of the test, he wrote... 7.) It comes in 2 attractive reusable containers. He got an A.