D. Pathogen. :) I hope it right :)
Distrust is a huge barrier in social relationships. Distrust often stems from a "me first" minset that leads to conflict. There is no "I" in team. When. trust is lacking we spend to much time. and energy resisting the other person. Selfies and attention seeking social media outlets has given life to lack of communication and distrust. A large population of individuals male and female would rather be desired by many except valued by one. I believe social media has destroyed many social relationships because a lot of people have more options than ever before. We live in a society of "more" and keeping up with the Joneses that we lack contentment in our social relationships sometimes.
I think it is natural selection. genetic variation also could be a factor for physical variation over the years.
Answer:
direct observation
Explanation:
because if your constantly monitoring them you should see any abnormal signs
