[Solved] What is the safest way or method to observe a solar eclipse? A) using a telescope B) wearing sunglasses C) by observing with your naked eyes D) through a pinhole projection E) through a UV filter held up to the sky Retrograde Pyelography: A diagnostic X-ray technique in which a contrast medium is introduced into the kidneys from the bladder to visualize the urinary system. Urethral Catheter: A pliable conduit placed via the urethra into the bladder for the purpose of draining urine. Contrast Medium: A substance used in medical imaging to improve the visibility of internal bodily structures in radiographic studies like MRIs and CT scans. Invasive Procedure: A medical test or operation that involves entering the body, often through cutting or inserting instruments into a body cavity.