Analysing topic sentences

Choose the best topic sentence for each paragraph below

1- Many politicians deplore the passing of the old family-sized farm, but I'm not so sure. I saw around Velva a release from what was like slavery to the tyrannical soil, release from the ignorance that darkens the soul and from the loneliness that corrodes it. In this generation my Velva friends have rejoined the general American society that their pioneering fathers left behind when they first made the barren trek in the days of the wheat rush. As I sit here in Washington writing this, I can feel their nearness. (from Eric Sevareid, "Velva, North Dakota")

2-There are two broad theories concerning what triggers a human's inevitable decline to death. The first is the wear-and-tear hypothesis that suggests the body eventually succumbs to the environmental insults of life. The second is the notion that we have an internal clock which is genetically programmed to run down. Supporters of the wear-and-tear theory maintain that the very practice of breathing causes us to age because inhaled oxygen produces toxic by-products. Advocates of the internal clock theory believe that individual cells are told to stop dividing and thus eventually to die by, for example, hormones produced by the brain or by their own genes. (from Debra Blank, "The Eternal Quest" [edited]).

3-Although the interpretation of traffic signals may seem highly standardized, close observation reveals regional variations across this country, distinguishing the East Coast from Central Canada and the West as surely as dominant dialects or political inclinations. In Montreal, a flashing red traffic light instructs drivers to careen even more wildly through intersections heavily populated with pedestrians and oncoming vehicles. In startling contrast, an amber light in Calgary warns drivers to scream to a halt on the off chance that there might be a pedestrian within 500 meters who might consider crossing at some unspecified time within the current day. In my home town in New Brunswick, finally, traffic lights (along with painted lines and posted speed limits) do not apply to tractors, all terrain vehicles, or pickup trucks, which together account for most vehicles on the road. In fact, were any observant Canadian dropped from an alien space vessel at an unspecified intersection anywhere in this vast land, he or she could almost certainly orient him-or-herself according to the surrounding traffic patterns.

Source: 

The Writing Centre. (2018). The Writing Centre | University of Ottawa. [online] Available at: http://arts.uottawa.ca/writingcentre/en/hypergrammar/writing-paragraphs/review-topic-sentences [Accessed 2 Jun. 2018].

Examples of Topic Sentences and How to Write Them

Summary:

The topic sentence (the first sentence of a paragraph) is a crucial part of writing and provides the reader the necessary information about what is going to be developed in the paragraph´s body.In order to be effective, it should be clear, precise and brief and it should avoid facts and phrases like: “I´m going to tell you…”

Good vs Bad topic sentences:

Abraham Lincoln was born in 1809. NO (it tells the reader very little about what you are going to say)

Abraham Lincoln, born in 1809, was one of the most influential politicians in history.   YES

The Civil War had lasting effects on South America. NO (the reason is not specified)

Because the Civil War was fought mostly on Southern soil, it had lasting effects on the region. YES

Source: 

KLAZEMA,A. (2014).Examples of Topic Sentences and How to Write Them.(online). available at: https://blog.udemy.com/examples-of-topic-sentences/ (accessed 2 jun. 2018).