**Core Concept**
Thyroid storm is a life-threatening complication of untreated or undertreated hyperthyroidism, often precipitated by a stressful event or a nonsteroidal anti-inflammatory drug (NSAID) use. It requires immediate medical attention and management.

**Why the Correct Answer is Right**
In this scenario, thyroidectomy alone would not be sufficient to cause a thyroid storm, as it typically takes several weeks for the body to absorb the radioactive iodine or for the thyroid gland to atrophy after surgery. However, if the patient was given an NSAID for pain relief, it could lead to the release of pre-formed thyroid hormones from the thyroid remnants, causing a thyroid storm. This is because NSAIDs can inhibit the peripheral conversion of T4 to T3, leading to a surge in T4 levels and subsequent thyroid storm.

**Why Each Wrong Option is Incorrect**
**Option A:** While thyroid storm can be caused by stress, this patient underwent surgery two days prior, which is not a typical cause of thyroid storm. Stress is more commonly associated with exacerbating pre-existing hyperthyroidism.
**Option B:** Radioactive iodine is used to treat hyperthyroidism, but it's not the most likely cause of thyroid storm two days after surgery. Radioactive iodine takes several weeks to take effect.
**Option C:** Thyroid hormone replacement therapy is not typically given immediately after thyroidectomy, making it an unlikely cause of thyroid storm in this scenario.

**Clinical Pearl / High-Yield Fact**
The use of NSAIDs in patients with hyperthyroidism can lead to a thyroid storm due to the inhibition of peripheral conversion of T4 to T3. This is a critical consideration in managing patients with hyperthyroidism, especially in the postoperative period.

**Correct Answer:** A.