Which of the following is not a degenerative corneal disease?

A female presented with swelling over the neck that moves with swallowing with lymphadenopathy at external jugular vein. Swallowing diagnosed as thyroid carcinoma.
She has most likely which type?

A 11-year-old boy comes with decreased appetite and abdominal pain around his umbilicus. His parents think he doesn't want to go to school, and while in math class he begins to have sharp pain in his right lower abdomen. He is rushed to the ED and laboratory analysis shows a WBC of 12,500.
What is the most likely diagnosis?

A 65-year-old lady who is on thiazide suffers from falls in the morning.
What is the cause for her symptoms?

Patient smoker and alcoholic come with difficulty in swallowing and neck mas.
What is an investigation?