EXPLANATION

Thesis sentences "a," "b," and "c" are all potentially usable as working theses for a research paper. Thesis "b" is an example of a working thesis for an ANALYTICAL research paper while thesis "c" is an example of a working thesis for an ARGUMENTATIVE research paper. Both "b" and "c" are researchable and, once you started to research, you'd probably find ways of defining the phrase "substantially helped." Yet the best thesis is thesis "a," since it already does specify the ways in which the whole language approach has helped elementary school children to read. Thesis "a" functions better as a working thesis, since it focuses the search in what might be a very broad field of benefits.