Answer :
Final answer:
Liam's experiment should use d.the amount of salt added to the soil as the independent variable and the growth rate of the geraniums as the dependent variable.
Explanation:
Liam's hypothesis is that increasing the amount of salt in the soil will cause a reduction in the growth rate of geraniums. To design his experiment, Liam should use the d.amount of salt added to the soil as the independent variable and the growth rate of the geraniums as the dependent variable. These variables are important because they allow Liam to determine the impact of salt on plant growth. The other options, such as the amount of fertilizer added to the soil and the flower color of the geraniums, are not directly related to Liam's hypothesis and would not provide the necessary data to test it.
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