A patient with carcinoma of tongue is found to have lymph nodes in the lower neck. The treatment of choice for the lymph nodes is:

Traditionally, the gold standard for control of cervical metastasis has been the radical neck dissection (RND). The classic RND removes levels I to V of the cervical lymphatics in addition to the SCM, internal jugular vein, and the spinal accessory nerve (CN XI). Any modification of the RND that preserves nonlymphatic structures (i.e., CN XI, SCM muscle, or internal jugular vein) is defined as a modified radical neck dissection (MRND). A neck dissection that preserves lymphatic compaments normally removed as pa of a classic RND is termed a selective neck dissection (SND). Ref: Weber R.S. (2010). Chapter 18. Disorders of the Head and Neck. In T.R. Billiar, D.L. Dunn (Eds), Schwaz's Principles of Surgery, 9e.