Which structure is a thick tract of white matter that interconnects the two cerebral hemispheres?

The correct answer is corpus callosum.

Explanation:

Corpus callosum is one of the compositions of the brain, which is situated within the cortex and above the thalamus. It is a thick tract of white matter, which associates the left and the right hemispheres of the brain. It is the component of the brain, which permits communication between the two cerebral hemispheres.

It performs an important role of conducting neural information between the two hemispheres of the brain.