To keep peace among Nations
The plural for would also be prey. But in more specific context the plural forms can also be preys, in reference to various types of preys.
The correct answer is internal.
Internal locus of control refers to when a person believes that he or she personally has control and responsibility for the outcomes in his or her life, and that external forces are not responsible for his or her life outcomes. For instance, a person with an internal locus of control is more likely to believe that his or her academic and job success (or lack thereof) lies in his or her control rather than in external factors such as others' intentions, unfairness, poor situations, etc.
The answer is C. Chinese parents didn’t value girls more than boys