题目内容：
根据以下材料，回答题ADHD finked to Air Pollutants
Children have an increased of attention problems seen as early as grade school. If their noses inhaled ( 吸入) a certain type of air pollution when they were pregnant. That's the finding of a new study, released when things aren't burned completely, this pollution is known as polycyclic aromatic hydrocarbons of PAHs.
The biggest sources of these PAHs: the bruning of fossile fuels, wood and trash. Frederica Perera works at Columbia University's Mailman School of public Health is Ne York City. She and her team studied the xposure to air pollution of 233 nonsmoking pregant women in New York City.
Because burning tobacco can spew (排放) PAHs into the air and lungs. Perera's team focused on nonsmokers.
The researchers investigated signs of attention problems in those children, now age 9. They asked each child's mother a series of questions. These included wahtever her child had problems doing things that needed sustained(长期的 )mental effort, such as homework or games with friends.
The scientists also asked if the kids had trouble following instructions or made grequent, careless mistakes. All of these can be sumptoms of a disorder called Attention Deficit Hyperactiviety Disorder, or ADHD. About one in U.S. children has ADHD. Among the women stueied traffic and home heating were the primary sources of air pollution exposure. Perera and her team suspect.
Some of these women had low levels of PAHs in their bolld. Others had ghigh levels. Those with high levels were five times as likely to have dhilren who showed attention problems by age 9. The new findings were published November 5 in the journal PLOS ONE.
Perera and her team chose nonsmiking pregnant women all over America. A．Right
B．Wrong
C．Not mentioned
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