This is called corpus callosum, or callosal commissure.
It is a part of your brain which connects the left with the right hemisphere and affects your entire body as well. Given that the left hemisphere controls the right part of your body (and vice versa), this is all done thanks to the corpus callosum in your brain.
Among the four choices above, the most likely to be the correct answer is the last one (letter d).
The culture hypothesis states that cultural beliefs are responsible for differences in prosperity.
Therefore,
the right choice for the statement with a blank space is non other than D
The central idea should be a complete declarative <span>sentence.</span>
I would go with D as the other three all say the same thing