Athesis statement is to a reader as is to it lets her know where the writer will take her.
car is to driver
roadmap is to passenger
student is to study guide
none of the above

The most probably answer among the presented options would be the one that says "road map is to passenger".

Let us establish first that we do not know what a thesis statement means and that we are just taking the statement as it is without any prior knowledge to the hard word present. The key to this would be the statement "it lets her know where the writer will take her." Among the ones presented as options, only the road map fits the description. Thus, the answer being road map is to passenger. The car is subject to the driver's commands thus the driver is the one guiding the car, and the student follows what is written in the study guide.

One splits the atoms and molecules  the other combines them