Final answer:
Intravenous cholecystography is used to visualize the gallbladder by injecting a contrast dye that helps identify abnormalities like gallstones.
Step-by-step explanation:
The X-ray that would be used to visualize the gallbladder is intravenous cholecystography (option B).
Intravenous cholecystography is a diagnostic procedure where a contrast dye is injected into the patient's veins. This dye is taken up by the liver and excreted into the bile, which flows into the gallbladder and then into the small intestine. The contrast dye helps to visualize the gallbladder and identify any abnormalities such as gallstones.
Option A (lower GI series) and option C (upper GI series) are X-rays used to visualize the gastrointestinal tract, but they do not specifically target the gallbladder. Option D (cholangiography) is an imaging technique specifically used to visualize the bile ducts.