**Core Concept**
Chronic myeloid leukemia (CML) is a type of cancer where the bone marrow produces too many white blood cells due to a genetic mutation known as the Philadelphia chromosome. The chronic phase is the initial stage of the disease, characterized by a relatively slow progression and a higher likelihood of treatment response.

**Why the Correct Answer is Right**
The treatment of choice for the chronic phase of CML is tyrosine kinase inhibitors (TKIs), which target the BCR-ABL protein responsible for the disease. Imatinib, a first-generation TKI, was the first drug to demonstrate significant efficacy in CML patients. It works by competitively inhibiting the ATP-binding site of the BCR-ABL tyrosine kinase, thereby preventing the phosphorylation of tyrosine residues and the subsequent downstream signaling.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because interferon-alpha has been used in the past as an alternative treatment for CML, but it has been largely replaced by TKIs due to their superior efficacy and tolerability.
* **Option B:** This option is incorrect because chemotherapy is typically reserved for the accelerated or blast crisis phases of CML, where the disease has progressed to a more aggressive stage.
* **Option C:** This option is incorrect because hydroxyurea is a cytoreductive agent that can be used to manage symptoms and reduce white blood cell counts in the short term, but it does not address the underlying molecular mechanisms of CML.

**Clinical Pearl / High-Yield Fact**
It's essential to note that CML is a disease characterized by a specific molecular abnormality, and targeted therapies have revolutionized its management. The development of next-generation TKIs, such as dasatinib and nilotinib, has further improved treatment outcomes for CML patients.

**Correct Answer:** D. Imatinib