Hello!! I think your best answer would be C - Sleep causes blood pressure to rise, and when he stood up quickly, he was hypotensive. Sleep will always raise your blood pressure, but your body is made to have your blood pressure to drop whenever you stand up. Have you ever felt the ringing in your ears and get super dizzy then sit down? It's because you are hypotensive. I hope I helped!! If you have any more questions then do not hesitate to message me. Have a great day!! :)