Which of these phrases best summarizes the trend represented by this graph?

The answer is: C

This is because the graph indicates the sharp decline of the rural population, due to in large part to the increase in urbanization and the ever-growing industrialization of the United States throughout the decades.

As such we can analyze that, as the years go by the population trends to move to urban areas in place of rural ones.

day one of being in trenches. i am very far away from home now. away from my beloved and beautiful wife and kids. oh how i miss you dear. it's only been a day out here, but its been a month away from home. how are the kids? i know lucy wanted to take art and john wanted to take his little karate lessons, how is that going? tell them i am proud of what they want to do. they make me proud! day 78, many of my beloved friends are gone, either dead in a ditch somewhere or literally lost. my best mate, paul is gone. he wanted to be a doctor and fall in love. he was very determined. it's awfully quiet now. lots of scattered hats from the perished soldiers. it rained the other day, theres mud all over my clothes, on top of that, i heard my new partner larry has lice! due to the rain and mud, there was a flood. i saw a foot in the trench the other day, on my way to base. we had to dig out some of the soldiers that got stuck in the mud. i heard there was also a break of chlorine gas! but i am fine. at least there arent any more rats! day 103, larry is gone. he died from a flood just like my other friendly soldiers. he said he was going to propose to his girlfriend when he gets home. we don't have time to barey the bodies. my captain told us to round up the bodies and just throw them on top of each other. i don't like it, bjt we really don't have time. they deserve a proper burial. dear, what do i tell his lady when we get back home? she'll be devastated. at least, i am glad that lucy is taking art. the drawings you sent me are just lovely! tell her i said keep up the great work! john js doing great with his karate too.