Final answer:
B. Systolic blood pressure 70 mmHg. The manifestation that indicates the client is experiencing autonomic dysreflexia (AD) is a sudden increase in blood pressure, causing a systolic blood pressure as low as 70 mmHg to increase dramatically.
Step-by-step explanation:
In a patient with cervical spinal cord injury, manifestations of autonomic dysreflexia (AD) can include a sudden increase in blood pressure, known as hypertensive crisis, which can cause a systolic blood pressure as low as 70 mmHg to increase dramatically. Therefore, option B. Systolic blood pressure 70 mmHg is the manifestation that indicates the client is experiencing autonomic dysreflexia (AD).