Sounds produced when space between vocal folds is closed completely (very briefly) and then released?

The sound produced when space between vocal folds is completely closed and then released is called glottal stop.

Explanation:

When the airflow in the glottis or the vocal tract is completely obstructed and then released, we have a consonantal sound called glottal stop or glottal plosive. Due to the obstruction, glottal vibration either becomes irregular or stops.

This sound is more common in certain languages than others. When it comes to the English language, it tends to happen more often in certain regional accents. For American speakers, it is usual to use the glottal stop in words such as curtain or mountain, when the /t/ phoneme is followed by a /n/ phoneme. Americans tend to interrupt the flow of air in the glottis as a means to connect both sounds. To better understand a glottal stop, think of the pause you make between the two syllables of the interjection "uh-oh". That pause is caused by the interruption of airflow in the glottis and is, thus, a glottal stop.

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.  

b is the answer