which of the following best describes the work of descartes?

a. he proved through calculus the existence of a heliocentric universe.
b. he proposed that through the use of reason and doubt individuals may arrive at understanding.
c. he demonstrated through observation of the night sky that planets orbit the sun. d. he confirmed christian teachings that the heavens are fixed and unmoving.

Rene Descartes ( 1596 - 1650 ) was very important scientist. He invented the Cartesian coordinate system. He considered mathematics like the basis to all sciences. Descartes partially agreed with Copernicus` theory about the Heliocentric system. He had his theory - "theory of the vertex".  because he was scared of the Catholic church, he didn`t totally agree with the Heliocentric system. He also had his "Method of doubt": Can`t be doubted = certainty = truth.
b. He proposed that through the use of reason and doubt individuals may arrive at understanding.   

I think the correct answer would be B. Descartes' work can be best describe as he is the the one who proposed that through the use of reason and doubt individuals may arrive at understanding. He destroyed all sources of knowledge for him to reach the certainty of knowledge called the Radical-Methodic doubt. He argues that knowledge would always start with doubting. Through this belief, it lead to the phrase "Cogito ergo sum" or I think, therefore I am was  which is a very famous quote used. From the said quote he was able to make other philosophical ideas which includes the existence of God.

The answer is option b and c.