A 22yrs male presented with chronic constipation,headache and palpitations.On examination he had marfanoid habitus,neuromas of tongue ,medullated corneal nerve fibers and nodule of 2x2 cm size in the left lobe of thyroid gland.The possible diagnosis is:

• A. MEN IIA
• B. MEN IIB
• C. Sporadic medullary carcinoma of thyroid
• D. Familial medullary carcinoma of thyroid