【单选题】

The United Nations declared 2011 to 2012 the Year of theBat. The campaign was launched as a way to strengthen efforts for protecting the world’s only flying mammal. These creatures can be found in many parts of the worlD、Bats live in cities, deserts, grasslands and forests. There are over 1,200 bat species.

The smallest bat in the world is from SoutheastAsiA、This kind of bat measures about 30 millimeters in length. The world’s largest bat, the Giant Golden-Crowned Flying Fox, has a wingspan of 1.5 meters. Most bats eat insects, but many feed on fruit or nectar from flowers.
Many people think bats are blind, but this is not true. Many species have very good sight. Most bats communicate and find their way by making "echolocation" (回声定位法) noises. They produce high-frequency noises and can estimate the distance of an object by using the sound echoes that bounce back to them. So, while bats may travel in total darkness, they "see" using sounD、
Sadly, bats are widely feared and misunderstooD、Most bats come out of their shelters only at nightfall. Three bat species feed on blooD、Because of these qualities, bats have long been linked in many cultures to death, darkness and blood-drinking.
Yet bats are important for agriculture and our environment. They help pollinate (授粉) plants and spread seeds. They also help control insects.Bats eat huge numbers of insects, including kinds that damage crops.
For example, a brown bat can eat more than 1,000 insects in one hour. One report says bats saveAmerican farmers billions of dollars every year by reducing crop damage and limiting the need for chemicals that kill insects.
Over one-fifth of all bat species are under threat. They face disease and the human destruction of their natural environments. In some areas, diseases have killed nearly 100% of bat populations.
Bats can fly in total darkness, because ______.
A、their eye sight is extremely sharp
B、they can fly without using their sight
C、they don’t have eye sight in daytime
D、they are very familiar with their environment