Which source would provide the most bias-free information about second hand smoke as a trigger of asthma?

Which of the following statements proves that scientific knowledge changed due to the discovery of the fossil of a hadrosaur in north dakota? hadrosaurs were better runners than earlier thought. hadrosaurs had no pattern on their skin as expected. the length of the hadrosaur was shorter than previously thought. the muscular structure of hadrosaurs was less developed than expected.