题目内容：
根据以下材料，回答题It'sone of our common beliefs that mice are afraid of cats.Scientists have longknown that even if a mouse has never seen a cat before, it is still able to detectchemical signals released from the cat and run away in fear.This has alwaysbeen thought to be something that is hard-wired into a mouse's brain.
But nowWendy Ingram, a graduate student at the University of California, Berkeley, haschallenged this common sense.She has found a way to "cure" mice oftheir inborn fear of cats by infecting them with a parasite, reported thescience journal Nature.
Theparasite, called Toxoplasma gondii, might sound unfamiliar to you, but theshocking fact is that up to one-third of people around the world are infectedby it.This parasite can cause different diseases among humans, especiallypregnant women--it is linked to blindness and the death of unborn babies.
However,the parasite's effects on mice are unique.Ingram and her team measured how micereacted to a cat's urine before and after it was infected by the parasite.Theynoted that normal mice stayed far away from the urine while mice that wereinfected with the parasite walked freely around the test area.
But that'snot all.The parasite was found to be more powerful than originallythought--even after researchers cured the mice of the infection.They no longerreacted with fear to a cat's smell,which could indicate that the infection hascaused a permanent change in mice's brains.
Why doesa parasite change a mouse's brain instead of making it sick like it does tohumans?
Theanswer lies in evolution.
"It'sexciting and scary to know how a parasite can manipulate a mouse's brain thisway,"Ingram said.But she also finds it inspiring."Typically if youhave a bacterial infection, you go to a doctor and take antibiotics and theinfection is cleared and you expect all the symptoms to also go away." Shesaid, but this study has proven that wrong."This may have huge implicationsfor infectious disease medicine."
Thepassage is mainly about_______. A．mice'sinborn terror of cats
B．theevolution of Toxoplasma
C．a newstudy about the effects of a parasite on mice
D．aharmful parasite called Toxoplasma gondii
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