Answer:
The correct answer would be the "at the bottom of the skull".
In organisms belonging to the genus Homo including humans, foramen magnum is large oval opening present at the base of the skull.
It allows the passage to the spinal cord to connect to the brain.
In addition, it allows arteries, nerves, and fluids to pass in and out of the brain. For example, cranial nerves, spinal arteries et cetera pass through the foramen magnum.
Lastly, the bottom location of foramen magnum aids in the bipedal locomotion of hominids.