**Core Concept**
Modified radical neck dissection is a surgical procedure that involves the removal of cervical lymph nodes, along with some surrounding tissues, to treat or prevent the spread of cancer. This procedure is typically performed for patients with head and neck cancer who have lymph node metastasis.

**Why the Correct Answer is Right**
Modified radical neck dissection includes levels II to V of the cervical lymph nodes. This is because these levels are more commonly involved in the spread of cancer from the head and neck region. The procedure involves the removal of lymph nodes from these levels, along with the sternocleidomastoid muscle, internal jugular vein, and spinal accessory nerve, depending on the extent of the disease. The removal of these structures helps to eliminate potential sites of cancer spread and recurrence.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because level I cervical lymph nodes are typically not included in a modified radical neck dissection. These nodes are located in the submental and submandibular regions and are not as commonly involved in head and neck cancer.

**Option B:** This option is incorrect because a radical neck dissection involves the removal of all cervical lymph nodes, including levels I to V, along with the sternocleidomastoid muscle, internal jugular vein, and spinal accessory nerve. A modified radical neck dissection, on the other hand, is a less extensive procedure that spares some of these structures.

**Option C:** This option is incorrect because a selective neck dissection involves the removal of specific levels of cervical lymph nodes that are involved by cancer, without removing any of the surrounding structures. This option is not correct because modified radical neck dissection includes more extensive tissue removal.

**Clinical Pearl / High-Yield Fact**
It is essential for surgeons to accurately identify the extent of lymph node involvement in head and neck cancer to determine the appropriate surgical procedure. Modified radical neck dissection is a critical procedure for patients with lymph node metastasis, and it is essential to understand the anatomy of the cervical lymph nodes to perform this procedure effectively.

**Correct Answer:** C. Levels II to V.