Answer:
A subject participates in a drug study because treatment is available at no or reduced cost, and he could not otherwise afford it. This is an example of:
c) Economic vulnerability
Explanation:
Economic vulnerability is strongly related to the socioeconomic status of the individuals and the nations they constitute. People who live in poverty tend to be more exposed/vulnerable to these types of situations as mentioned in the case, because they do not have access to resources to protect and take care of themselves.
