A

    Most Americans start to school at the age of five when they enter kindergarten(幼儿园). Children do not really study at this time. They only attend for half the day and learn what school is like. Children attend elementary school for the next six years. They learn to read and write and work with numbers. They also study the world and its people. After they leave elementary school, children go to junior high school for three years and senior high school for another three years. This is called secondary education. In some places, the children go to elementary school for eight years and high school for four. In all, elementary and secondary education together take twelve years to complete excluding （不包括）kindergarten.

根据短文，选择最恰当的选项。  

下列关于青霉和乳酸菌的比较中，说法正确是（　　）