<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 20-year-old man presents with a painless neck mass that has gradually increased in size. The mass is anteromedial to the right sternocleidomastoid muscle and has been present for 3 years. The mass increased in size and became more tender following an upper respiratory infection. An ultrasound of the neck identifies a single, round cystic mass with uniform, low echogenicity, and no internal septations. A contrast-enhanced CT scan of the neck shows a homogeneous mass with low attenuation centrally and with smooth rim enhancement. Which of the following is the most likely diagnosis?? A: First branchial cleft cyst, B: Ectopic thyroid tissue, C: Second branchial cleft cyst, D: Sternomastoid tumor, E: Cervical lymphadenopathy,  <response>: This is a clinical case scenario describing a 20-year-old man with a painless neck mass that has been present for 3 years and recently increased in size and tenderness after an upper respiratory infection. Key findings include:- Location: anteromedial to right sternocleidomastoid muscle- Duration: 3 years - Recent increase in size and tenderness after URI- Ultrasound shows cystic mass, no internal septations, uniform low echogenicity - CT shows homogeneous mass, low attenuation centrally, smooth rim enhancementBased on the location, cystic nature, and imaging findings, this is most consistent with a branchial cleft cyst. The location anterior to the sternocleidomastoid specifically points to a second branchial cleft cyst as the most likely diagnosis. Ectopic thyroid tissue, sternomastoid tumor, and cervical lymphadenopathy would not present in this location or with these imaging characteristics.C: Second branchial cleft cyst 