The primary factor that hindered both Galileo and Descartes in their work was C. the Catholic Church.
Galileo faced significant opposition from the Church due to his support of the heliocentric model, which contradicted the Church's geocentric views and interpretations of Scripture. This opposition culminated in his trial and house arrest.
Descartes, while not directly persecuted like Galileo, was also affected by the prevailing religious and philosophical climate of his time, which was influenced by Church doctrine. His ideas were often cautious and shaped by the need to avoid conflict with established beliefs.
While other factors such as "A. a lack of resources" and "D. the opinions of others" may have played roles in their experiences, the most significant hindrance they encountered was the powerful influence of the Catholic Church.