Final answer:
A positive Chvostek's sign, which occurs when tapping the facial nerve causes muscle spasms, can indicate hypocalcemia in a client. Therefore, the correct option is b.
Step-by-step explanation:
A nurse suspects a client may have hypocalcemia based on a positive Chvostek's sign. The Chvostek's sign involves tapping the facial nerve and watching for muscle spasms, which is indicative of hypocalcemia. This symptom is associated with low calcium levels affecting nerve excitability and muscle contraction. Other signs such as the Babinski sign, Homan's sign, or Goodell's sign are related to different neurological or physiological conditions and would not be used to diagnose hypocalcemia.