[Solved] The difficulty in calculating a tax is typically in the determination of: A) The correct tax rate B) Where to file the tax return C) The tax base D) The due date for the return E) None of these Optical Microscope: A type of microscope that uses visible light and a system of lenses to magnify objects, allowing for the observation of small details not visible to the naked eye. Illuminating: Providing light to an area or making something clearer and more understandable. Iris: The colored part of the eye, made of muscular tissue that contracts and relaxes, altering the size of the pupil. Glucometer: A medical device used for determining the approximate concentration of glucose in the blood.