A、Criminals who set the fires on purpose. B、Natural lightning strikes. C、Sparks from vehicles. D、Carelessly discarded cigarettes

Bushfires in southeastern Australia have killed 108 people and the authorities are warning that the number of victims could increase as outbreaks continue to burn out of control. Giant walls of flame have destroyed hundreds of homes, forests and farmland in the country’s worst ever wildfire disaster. Witnesses recount seeing trees explode and the sky raining ash as temperatures reach 47 degrees Celsius.
    Up to 400 fires raged around the southern city of Melbourne, devouring hundreds of homes and vast areas of forest and farmland. There are concerns that entire towns may have been lost. Charred bodies have been found in cars. It is thought many of the victims had tried to escape the attack only to be overcome by its sheer speed. Many communities have seen whole streets reduced to smoking ruins, with piles of blackened bricks and iron roofing sheets twisted in the heat, while burned-out cars littered the roadside.
    Touring the devastated region, Australian Prime Minister Kevin Rudd said he was "absolutely horrified" by the disaster. Thousands of exhausted volunteer firefighters are still battling dozens of uncontrolled outbreaks in Victoria, although conditions have eased considerably in the past 18 hours. (26)Australian government officials said the army would be deployed to help out, and officials have announced immediate emergency aid of seven million dollars.
    (27) Australia’s deadliest fires were in 1983, when blazes killed 75 people and destroyed more than 3 000 homes in Victoria and South Australia.
    The continent’s southeastern corner is one of the world’s most fire-prone regions. (28)Police have said that half of all bushfires are set deliberately. Others are started by lightning strikes, sparks from trains or accidentally by discarded cigarettes.