Question

read the paragraph. then, add the best concluding sentence.
theres a new kind of \crop\ popping up all across america—wind turbines. wind turbines are large machines that change wind energy into electricity. most wind turbines are tall poles with three giant blades. the blades catch the wind and spin. this motion is used to make electricity. large groups of these wind turbines are called wind farms. wind farms can cover hundreds of square miles of land, or they can be placed out at sea. they are built in places with strong, steady winds. though there are downsides to wind farms, the power they create does not produce air pollution. because of this, wind turbines are becoming a more common sight in the united states.
one of the largest wind farms in the u.s. is roscoe wind farm in texas.
wind turbines usually have three spinning blades high in the sky on top of poles.
because of this, wind turbines are becoming a more common sight in the united states.
as a result, wind farms are not being used in the u.s. yet.

Explanation:

The question seems to be about finding the best continuing sentence for the paragraph about wind energy and wind farms. The original text talks about wind turbines becoming common in the US. The option "Because of this, wind turbines are becoming a more common sight in the United States." logically connects to the previous content (mentioning the power they create without pollution, leading to their increased presence) and continues the topic of wind turbines' prevalence. Other options either introduce new details (like specific wind farms or turbine design) which are less about continuing the main idea of their commonality.

Answer:

Because of this, wind turbines are becoming a more common sight in the United States.