How does the author emphasize the widespread impact of the radioactive
water that leaked as a result of the tsunami?
A. The author explains that the Japanese power plant did nothing to
stop the leaking water.
B. The author explains that radioactive chemicals were found in the
Pacific Ocean near California and Canada.
C. The author explains that the Japanese nuclear power workers
contaminated the waters themselves.
D. The author explains that the radioactive chemicals did not actually
leak from the Daiichi facility.

a complex sentence consists of an independent clause and one or more dependent clauses.  

to write complex sentences, we must use subordinating conjunctions.  

all the complex sentences begin with a subordinating conjunction and when it occurs, a comma must be place at the end of the dependent clause. on the contrary, if the sentence begins with an independent clause, then no comma is used.

after  

although  

as  

because  

before  

if  

since  

when  

for example,  

after she won the competition, she became very popular.  

although my father was hurt, he continued fighting for his rights.  

as all of you got a ten, you will be able to leave early today.  

before he went to the war, he asked his parents to bless him.  

if it is cold, i won’t go out.  

since you didn’t bring the homework, you will get low grades.  

when it is hot in the town, everyone goes to the beach.