Final answer:
The bullet is lodged in the brain, leading to immediate cessation of breathing and heartbeat, making option A) In the Brain the correct answer.
Step-by-step explanation:
Based on the scenario given in the question, if the bullet entered the brain causing immediate cessation of both breathing and heartbeat, it suggests that the bullet is lodged in the brain.
This kind of traumatic impact to the brain would be catastrophic, disrupting essential neurological functions critical for life, such as those controlling the heart and lungs.
Hence, the mentioned correct option in the final answer is A) In the Brain.