Based on the nature of auxins discussed in the previous section and the explanation of photo-and geotropism, explain how auxins could cause hydrotropism.

Auxins are the phytohormone that helps in cell elongation and division as well

Explanation:

Auxin specifically present on the tips of lateral roots and it facilitates the bending of roots towards various environmental stimuli like hydrotrophism.  Its exact mechanism is the topic of interest for researchers. But it is clear that It works with gene expression that helps in cell elongation and division in response to the stimuli here in case "water" resulting in the larger growth of one part as compared to other parts of root. the most common and well known auxin is Indole acetic acid (IAA)

the question isn't complete here so i can't right an answer '_'

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.