A patient’s abdomen (alimentary canal) can be examined by X-ray after administering which one of the following metal salts in the patient’s meal?

Which one of the following parts of human alimentary canal can be of maximum length?

Which one of the following salts is found in maximum amount in the human bones?

Which one of the following radio elements is used to measure the speed of the blood flow in the human body?

Which one of the following statements best describes the role of B cells and T cells in the human body?

Which one of the following statements is correct?