kaila is treating patient at scene of an automobile accident and she is having difficulty in hearing patient's voice due to police sirens, so such kind of communication barrier that which could be either environmental or natural condition that does not allow the transfer of message from one person to the other is called 'physical barrier'.
Physical barriers do not allow the communication to be effective. Hearing problems due to thunders, sirens, call disconnection, message not sending all come under physical barriers.
The answer is D because when you get a head injury your most likely to have a concussion from the impact which will cause you to loss consciousness and have blurred vision and dizziness.
