It would make the curve go in an upwards manner...
Basically, figure out how the 'path' compares to life. Life can be easy (very level) and beautiful (very serene) but it can also be difficult and full of hardship (winding and full of undergrowth). Life can go in different directions and present one with many choices (fork into several directions) and life or things in life can help you realize where you want to go, and what you want to do (landmarks and signs). And lastly, life has an end (as paths do).
I believe the answer is: conducting research to learn about the social world
The research in sociology is usually done in order to uncover whether a certain situation created by society affect the lives of the smaller social group. Rather than relying only on the words from authority, it reveal the perspective of all people involved starting from the bottom of society all the way to the power holders.
The correct answer is the physical environment
There are several factors that contribute to change and innovation in a society: factors internal to the society itself or external factors of the environment that surrounds it. Nowadays, the extreme importance of the relationship between society and its environment has become very clear. The environment is not only a crucial source for the maintenance of society with its climatic and geographic characteristics in general, its natural wealth, its sources of energy, its flora and fauna, all functioning as a set of conditions in relation to which the society must adapt. In this process, society can interact with its environment in different ways and directions: either contributing to improve or to worsen and impair its living conditions. Changes in the environment end up forcing changes in society. Societies, throughout history, have needed to adjust to changes in the environment. This is an unquestionable adaptation process.
The environment to which a society must adapt also includes other societies with which it maintains contact. A major change in one tends to trigger a chain process with consequences for the others and forcing adjustments and innovations.
But there are other sources of change. The dynamics of forces within societies, which are part of the human condition itself, prevent society from remaining permanently stable. First, in the transmission of cultural heritage from one generation to another, changes of various types occur. As we saw earlier, individuals are not passive in forming habits, learning customs and receiving information as they grow and develop. Human beings are apparently, by their very nature, motivated to try new patterns of action. Motivation is often the simple curiosity that can be intensified by the cultural world. Or, the motivation may be simple material self-interest. Men seek to maximize their rewards, that is, to earn more and better as a result of their actions. In this way, experimentation and innovations are inevitable.
