Which of the following passes through the foramen Magnum ?

The veebral aeries - The veebral aery on each side is a branch of first pa of subclan aery. it's course is divided into 4 pas : 1) 1st pa lies from its origin to the foramen transversarium of 6th cervical veebra, 2) 2nd pa courses through formen transversarium of 6th to 1st cervical veebra, 3) 3rd pa lies on the posterior arch of atlas veebra, 4) 4th pa of the veebral aery enters the cranium through foramen magnum under the free margin of posterior atlanto-occipital membrane. REF : B D Chaurasia's Human Anatomy , seventh edition , volume 2 , pg. no., 168.