Answer:
the growth of her corpus callosum
Step-by-step explanation:
The corpus callosum is known to be the connector between brain hemispheres, which means that it connects the left side of the brain to the right side. It is this connection that permits for the transfer of information between the two sides of the body. Hence the ability for Elise to write with one hand and steady the paper with the other is as a result of a connection between her left and right brain, which shows growth in her corpus callosum.