Miss D has many pairs of shoes in her wardrobe and wants to find out which pair of shoes she can run the fastest in. She chooses three pairs of shoes to try out: high heels, Nike running shoes, and her hiking boots. She will run 425 meters on the same paved running surface, in the same weather conditions, and use the same stop watch for each trial. She will measure the amount of time it takes her to run 425 meters in each pair of shoes. Results:
1. When running in the high heels, it took Miss D 2 minutes and 33 seconds
2. When running in the Nike running shoes, it took Miss D 0 minutes and 45 seconds
3. When running in the hiking boots, it took Miss D 1 minute and 15 seconds

What is the independent variable in this experiment?

1.Weather Conditions

2.Type of shoes worn

3.Time it took to run 425 meters