Answer:
Null Hypothesis = Depression levels among two groups equal, Alternate Hypothesis = Depression levels among two groups unequal.
Step-by-step explanation:
Null Hypothesis is the neutral hypothesis, of no difference.
Null Hypothesis in this case is, mean depression level among victims = mean depression level among bystanders.
Alternate Hypothesis in this case is, mean depression level among victims ≠ mean depression level among bystanders.