<span>You discover that the underlying cause of a disease is a protein that is less stable than the non-disease-causing version of the protein. this change is most likely to be due to </span>
Hypothesis.
A Hypothesis is an estimation of what might happen and the student's observation before moving on to investigate.
D the discovery of genes changed how scientists think about life
I don't know witch definition you mean, but here: https://www.google.com/search?q=google+dictionary&rlz=1C1CHBF_enUS871US871&oq=google+dic&aqs=chrome.0.0j69i57j0l6.3972j0j7&sourceid=chrome&ie=UTF-8#dobs=blowout