Among the options provided, the factor that might cause an increased use of traditional medicine in 21st century western societies is:
C. The Internet has made information on and availability of traditional medicine easily available.
The easy accessibility of information and availability of traditional medicine through the Internet can contribute to an increased interest and use of such practices. It allows individuals to explore alternative approaches to healthcare and gain knowledge about traditional medicine remedies, practices, and philosophies. This accessibility can influence people's choices and potentially lead to an increased utilization of traditional medicine in western societies.