Select the Correct Sequence for Proving Koch's Postulates

Multiple Choice

Select the correct sequence for proving Koch's postulates.
1)  The microorganism must be recovered from the experimentally infected hosts.
2)  The microorganism must be present in every case of the disease.
3)  The same disease must be produced when a pure culture of the microorganism is introduced into susceptible hosts.
4)  The microorganism must be grown in pure culture from diseased hosts.

A) 2, 4, 3, 1
B) 1, 2, 3, 4
C) 1, 3, 2, 4
D) 4, 3, 1, 2
E) 4, 1, 2, 3