Final answer:
A reasonable hypothesis for Jessica's experiment is if plants are watered with saltwater, then they will show signs of wilting.
Step-by-step explanation:
A well-written hypothesis is a prediction of the results of an experiment with an explanation as to why you believe this prediction will occur. For Jessica's experiment, a reasonable hypothesis could be:
If plants are watered with saltwater, then they will show signs of wilting.
This hypothesis is testable and has an if-then statement format. The independent variable is the saltwater, and the dependent variable is the wilting of the plants. By conducting an experiment and comparing the growth and condition of plants watered with saltwater to those watered with freshwater, Jessica can gather evidence to support or reject her hypothesis.