Article: One day a teacher was giving her young students a lesson on how the government works . She was trying to explain the principle of income tax  . "You see ," she began , speaking slowly and carefully , "each person who works must pay part of his or her salary   to the government . If you make a high salary , your taxes are high . If you don't make much money , your taxes are low ." "Is that clear ?" she asked . "Does everyone understand the meaning of income tax ?" The students nodded. "Are there any questions ?" she asked . The students shook their heads . "Very good !" she said . "Now ,I would like you to take a piece of paper and write a short paragraph on the subject of income tax ." Little Joey was a slow learner . He had lots of problems with spelling and grammar , but this time he at least seemed to understand the task . He took his pen and after a few minutes , he handed the teacher the following composition : Once I had a dog . His name was Tax . I opened the door and in come Tax . 
 Question: The teacher was trying to explain  _  one day . 
 Options: (A) the basic principles of the income tax (B) how the government works (C) everyone should pay income tax (D) how much tax one should pay for his income
A