Answer: Frontal lobe
Step-by-step explanation:
Frontal lobe is the section present in human brain that is responsible for regulating cognitive functions in body.It helps in expressing emotions, judging language, solving issue , controlling personality, memory etc. Symptoms like irritation, mood change or swing etc can take place after damage occur in this lobe.
According to the question,Mark has injured his brain's frontal lobe most probably due to which he is not able to regulate behavior and cognitive functions. He gets distracted, irritated and impulsive trait after accident.