Question

heartburn is usually caused by the effects of gastric juice on the _________.
multiple choice
stomach
small intestine
esophagus
heart

Explanation:

Heartburn occurs when stomach acid (gastric juice) flows back into the esophagus. The stomach has a protective lining against gastric juice, the small intestine neutralizes acid, and the heart is not related to gastric juice reflux.

Answer:

esophagus