The right option is; d. plasticity
The neurologist bases this diagnosis on the plasticity of Brendan's brain.
Brain plasticity is the ability of the brain to change and adapt to new experiences throughout a person’s life. The brain has the unique ability to readjust itself and modify its connections by creating new neural pathways between brain cells. Plasticity of the brain can take place when; (i) there is case of brain injury in which the brain will recover lost functions or increase the efficiency of remaining functions, (ii) at the beginning of life during infancy and childhood when the brain is not mature and (iii) through adulthood when new things are learned or experienced.
