Answer:
Figure 3 is more helpful than figure 2 since it shows a clearer trend in the data, while figure 2 does not.
Explanation:
Parietal cells produce gastric acid (hydrochloric acid) in response to histamine (via H2 receptors), acetylcholine (M3 receptors) and gastrin (gastrin receptors). Parietal cells contain an extensive secretory network (called canaliculi) from which the HCl is secreted by active transport into the stomach.
