[单项选择]

Text 2
SoBig. F was the more visible of tile two recent waves of infection, because it propagated itself by e-mail, meaning that victims noticed what was going on. SoBig. F was so effective that it caused substantial disruption even to those protected by anti-virus software. That was because so many copies of the virus spread that many machines were overwhelmed by messages from their own anti-virus software. On top of that, one common counter-measure backfired, increasing traffic still furthers. Anti-virus software often bounces a warning back to the sender of an infected e-mail, saying that the e-mail in question cannot be delivered because it contains a virus. SoBig. F was able to spoof this system by "harvesting" e-mail addresses from the hard disks of infected computers. Some of these addresses were then sent infected e-mails that had been doctored to look as though they had come from other harvested addresses. The latter were thus sent warnings, even
A. Computer scientists are quit optimistic about the existing anti-virus programs.
B. Computer scientists are looking forward to the coming anti-virus programs.
C. Computer scientists consider the existing viruses not the really destructive ones.
D. Computer scientists regard the coming viruses as the really destructive ones.