I believe it would be option A. If it still doesn't answer your question, don't hesitate comment below. :)
A series of radiographic images taken of the stomach and duodenum after the contrast agent barium has been swallowed is an upper GI series, where
GI<span> stands for "</span>gastrointestinal<span>," which means "stomach and intestines".
</span>This x-ray examination of the upper gastrointestinal<span> (</span>GI<span>) tract,</span>can diagnose problems in your upper GI tract, how to prepare for the procedure, and what to expect afterwards.
There are four total electrons to balance out the four protons
