Answer:
The answer is: letter D, using reason and observation to solve a problem.
Step-by-step explanation:
Renee Descartes was a French philosopher who founded the modern philosophy while Francis Bacon was an English philosopher who developed the scientific method. According to both of them, a critical step in reaching a sound scientific conclusion is by using reason and observation in order to solve it.
Observation and perceptual experiences co-existed in order to predict the outcome. In order to solve a problem, the necessity to reason out is important. The solution needs to have a reason in order to aid the readers how the researcher came up with it.
For example, Renee Descartes employed the cause-and-effect method when it comes to problem solving. He emphasized that reason was the main source of the researcher's knowledge.
Thus, this explains the answer.