This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Anatomy
All the following are true regarding oat cell carcinoma of lung except 
Select and explain. 
A. Varient of large cell anaplastic CA, B. Chemotherapy is effective, C. Paraneoplastic syndrome may be present, D. Causes SIADH
A: Varient of large cell anaplastic CA
Answer: A: Varient of large cell anaplastic CA 
Explanation: Oat Small-cell carcinoma (oat cell) and adenocarcinoma of the lung, although the most common lung tumors associated with skeletal metastases, rarely cause Many solid tumors associated with hypercalcemia, paicularly squamous cell and renal tumors, produce and secrete PTHrP that causes increased bone resorption and mediate the hypercalcemia through systemic actions on the skeleton. Ref Harrison 19th edition pg 2476