Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: During a lab investigation, students were asked to determine the best way to clean up an oil spill using different materials. Investigation Materials • filter paper • foam sponge • metal wire screen • thin sock filled with hair The students tested the materials by placing each material into separate buckets containing oil and water. They recorded their observations on which material absorbed the most oil. Why would the students' teacher ask them to repeat their tests?
to improve the chances of obtaining accurate oil cleanup results
To ensure accuracy and reduce errors.