Using the information provided, indicate which statistical test you think should be used for each of the following situations:
a. Independent variable: normal birth weight vs. low birth weight infants; dependent variable: 1 minute Apgar scores (1-10 scale).
b. Independent variable: time of measurement (before, during, and after surgery); dependent variable: heart rate.
c. Independent variable: time of measurement (before, during, and after intervention); dependent variable: did vs did not exercise regularly.
d. Independent variable: infertility treatment A vs infertility treatment B vs control condition; dependent variable: did vs did not become pregnant.