[单项选择]

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When a Massachusetts biotech company recently declared that its researchers had cloned human embryos, it conjured up scary images for many people: bad science-fiction movies, Hitler’s twisted ambitions, rows and rows of identical humans.
But, like most things in life, the truth is a lot more complicated, more subtle.
The announcement drew a storm of criticism. Ethicists, religious leaders and US President Bush denounced Advanced Cell Technology for going too far. Scientists charged that the experiment was hyped and called it a failure.
The news put a spotlight on the field of cloning, from work with animals to researchers’ efforts to use cloning to create tissues for people suffering from debilitating and fatal diseases.
At its most basic level, cloning means creating copies, and in many ways, cloning has been around a long time. When someone cuts a shoot off a green spider plant and re-p
A. Scientists haven’t got the faintest idea at all.
B. Scientists haven’t researched into the cause.
C. Scientists speculate that there must be something wrong in the genetic reprogramming.
D. Scientists calculate that those animals are susceptible to diseases.