Final answer:
Damage to the prefrontal cortex can lead to impaired decision-making and impulsivity (option a). This area of the brain is responsible for functions such as planning, judgment, and reasoning, as well as personality and social behavior.
Step-by-step explanation:
When the prefrontal cortex of the brain is damaged, it can result in a variety of cognitive and behavioral problems. This part of the brain is essential for high-order functions such as planning, judgment, reasoning, and working memory. Additionally, it plays a significant role in personality and social behavior.
The landmark case of Phineas Gage illustrates the profound effect that damage to the prefrontal cortex can have on an individual's personality. Similarly, the now-obsolete medical procedure of prefrontal lobectomy also demonstrates how alterations to this brain region can lead to changes in behavior and personality.
Given its functions, when the prefrontal cortex is impaired, one may observe impaired decision-making and impulsivity. Such damage could lead to difficulty with planning and executing tasks, poor judgment, and personality changes, which are not congruent with enhanced memory, learning abilities, increased sensory awareness, or motor coordination. Hence, option (a) 'Impaired decision-making and impulsivity' is the correct option regarding the possible effects of damage to the prefrontal cortex.