Final answer:
For an experiment with one manipulated independent variable and a measured dependent variable, specifically with more than two groups to compare, the appropriate statistical test is B. ANOVA.
Step-by-step explanation:
When conducting an experimental study with an independent variable and a dependent variable, researchers often use various statistical tests to analyze the data collected. In your case, the independent variable is the treatment group (visual stimulation, auditory stimulation, or no special stimulation), which is being manipulated to investigate its effect on the dependent variable, which is the infants' length of stay in the hospital after birth. The most appropriate statistical test to compare means between more than two groups is Analysis of Variance (ANOVA). A t-test is generally used when comparing the means of two groups. A Chi-square test is used for categorical data to test for independence between variables. Pearson's r is used to measure the strength of association between two continuous variables. Thus, the correct answer to your question about which statistical test to use is B. ANOVA.