All of the following sentences are complex EXCEPT

A) Even though acid rain can have damaging effects, few people know much about it.
B) Acid rain has been studied as an environmental issue by the government since the 1970s.
C) Since they erode statues and corrode steel structures, the chemicals in acid rain are harmful.
D) Since the Industrial Revolution began, emissions of sulfur dioxide and nitrogen oxide have increased.

C maybe

And your answer is?

No, not C.

No, not A.

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http://www.grammar-monster.com/glossary/complex_sentence.htm

B 100%

To determine which of the sentences is not complex, we need to understand what a complex sentence is.

A complex sentence is a sentence that consists of an independent clause and at least one dependent clause. An independent clause can stand alone as a complete sentence, while a dependent clause cannot.

Let's analyze each sentence:

A) "Even though acid rain can have damaging effects, few people know much about it."
This sentence contains a dependent clause ("Even though acid rain can have damaging effects") and an independent clause ("few people know much about it"). It is a complex sentence.

B) "Acid rain has been studied as an environmental issue by the government since the 1970s."
This sentence only contains an independent clause and does not have a dependent clause. It is not a complex sentence.

C) "Since they erode statues and corrode steel structures, the chemicals in acid rain are harmful."
This sentence contains a dependent clause ("Since they erode statues and corrode steel structures") and an independent clause ("the chemicals in acid rain are harmful"). It is a complex sentence.

D) "Since the Industrial Revolution began, emissions of sulfur dioxide and nitrogen oxide have increased."
This sentence only contains an independent clause and does not have a dependent clause. It is not a complex sentence.

Based on this analysis, the sentence that is NOT complex is B) "Acid rain has been studied as an environmental issue by the government since the 1970s."