According to the passage, how is alcohol finally returned to the mother's system?

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 30 to 34  

     According to the American College of Obstetrics and Gynecology, pregnant women should not drink any form of alcohol. Pregnant women who think they have should be aware of the serious and negative effects alcohol on the development of the baby (fetus).  

     Alcohol is considered one of the most dangerous drugs for women during their pregnancy. Because alcohol is delivered quickly into the blood and passes quickly into the tissues and membranes, the human fetus is particularly vulnerable to its effects. The reality is that the negative effects on a fetus are so pronounced that babies born after exposure to alcohol are said to be suffering from fetal the syndrome. As a pregnant woman drinks alcohol, the alcohol is passed into her bloodstream almost simultaneously. Moreover, because the bloodstream of the fetus is inextricably tied to that of the mother, the alcohol passes directly into the bloodstream of the fetus as well. And, what is more, the concentration of alcohol in the fetus is exactly the same as in the mother.  

     For the mother, this concentration is not a problem because her liver can remove one ounce of alcohol from her system per hour. However, the fetus's liver is not completely developed (how developed it is depends on its stage of development). The rate at which it is able to eliminate the alcohol from the blood of the fetus is much slower. Eventually, the alcohol will be returned to the mother's system by passing across the placenta, but this process is slow. By the time this takes place, major neurological damage may have already occurred.  

     Research has shown that as little as one drink of alcohol can produce significant, irreversible damage to the fetus. Babies born after exposure to alcohol generally exhibit facial distortion, inability to concentrate, and difficulty in remembering. Simply speaking, it is imperative that pregnant women avoid alcohol.  

What is the main topic of this reading?

The rate of inflation has fallen steadily during recent months.

“It would be a good idea that we should try to get local support for the new motorway”, said Joe.

James: “It was very kind of you to give me a lift home".  

                     Pete: “___________”