Much of what we know about left and right hemisphere specializations comes from the study of people who had split-brain surgery. this surgery select one:

a. splits the lobes of the brain apart.
b. severs the corpus callosum between hemispheres.
c. severs the nerves from the spinal cord to the right hemisphere.
d. severs the substantia nigra between hemispheres.

b. severs the corpus callosum between hemispheres.

Step-by-step explanation:

The split-brain surgery is used to alleviate epileptic seizures. It involves the severing of the corpus callosum, that is the bond between both hemispheres of the brain.

So the correct answer is:

b. severs the corpus callosum between hemispheres.

The ratio of blue marbles to red marbles is 35:15. To test his hypothesis in the best way, he should make sure that the total number of marbles he draws is 100. In other words, both sides of the ratio added together should equal 100. Right now, both sides equal 50 (35 + 15 = 50). To get to 100, double both sides of the ratio. Now, the ratio is 70:30. Based on the 50 marbles Sam drew, there are 70 blue marbles and 30 red marbles, meaning Sam's hypothesis is incorrect, and there are more blue marbles than red.