Final answer:
Yeast is an inappropriate leavening agent for a deep fry batter because it requires time to work, which is not available in the quick cooking process of deep frying.
Step-by-step explanation:
An inappropriate leavening agent for a deep fry batter would be yeast. Deep frying is a quick cooking process, and yeast requires time to ferment and produce carbon dioxide, which makes it unsuitable for such rapid cooking methods. In contrast, baking powder, which often contains sodium bicarbonate and an acidic substance like sodium aluminum sulfate, releases carbon dioxide quickly when moistened and heated, making it ideal for deep frying batters. Baking soda, sodium bicarbonate, also needs an acidic ingredient to react and produce carbon dioxide, and it's commonly used in batters as well. Finally, salt, though not a leavening agent, is included in batter recipes for flavor.