**Core Concept**
The patient is experiencing a side effect triad of tremor, thyroid enlargement (goiter), and leucocytosis, which is likely due to an underlying medication effect on thyroid function and the hematopoietic system.

**Why the Correct Answer is Right**
The correct answer is **Haloperidol**. Haloperidol is a typical antipsychotic medication that can cause extrapyramidal side effects such as tremor. It can also cause an increase in thyroid-stimulating hormone (TSH) levels, leading to thyroid enlargement (goiter), and can induce a leucocytosis by stimulating the release of white blood cells from the bone marrow. This is due to its dopamine D2 receptor antagonism, which affects the hypothalamic-pituitary-thyroid axis and the hematopoietic system.

**Why Each Wrong Option is Incorrect**
* **Option A:** Chlorpromazine is another typical antipsychotic medication, but it is less likely to cause leucocytosis and thyroid enlargement compared to haloperidol.
* **Option B:** Risperidone is an atypical antipsychotic medication that is less likely to cause extrapyramidal side effects and thyroid dysfunction compared to haloperidol.
* **Option C:** Amitriptyline is a tricyclic antidepressant medication that can cause weight gain, sedation, and anticholinergic side effects, but it is not typically associated with the side effect triad of tremor, thyroid enlargement, and leucocytosis.

**Clinical Pearl / High-Yield Fact**
When prescribing antipsychotic medications, it is essential to monitor for extrapyramidal side effects, thyroid function, and hematological parameters to prevent and manage potential side effects.

**Correct Answer: D. Haloperidol**