Explanation
Correct answer: B.
Choice B is the best answer. The sentence contrasts how green backgrounds are used in US and UK road signs, noting that the US uses them for both highways and major roadways while the UK uses them only for major roadways.
Why the other choices are wrong
Choice A
Choice A is incorrect. While the sentence does contrast US and UK road signs, the contrast focuses on the use of blue versus green backgrounds rather than on the use of green backgrounds specifically.
Choice C
Choice C is incorrect. The sentence indicates a similarity between the uses of green road signs in the US and the UK rather than contrasting them.
Choice D
Choice D is incorrect. The sentence indicates a similarity between road signs in the US and those in the UK; it doesn’t contrast how green backgrounds are used in each country’s signs.