Themselves
This reflexive pronoun is the best fit because it needs to agree with the antecedent--in this case "scholars". Because scholars is plural, the pronoun also needs to be plural. Themselves is a plural reflexive pronoun, so it will properly complete the sentence.
Make a mathmatecal, chemical, or grammatical study of
Because the organization depends on how you will be making the essay because if you did order of importance than your central idea would most likely be developed in the beginning, but if it was like order of like same and difference then the central idea would be tough to put in you would have to put the central idea at the end to clarify why you did the order of same and difference.
