Answer:
D: It travels from computer to computer in a network, but it does not usually erase data.
Explanation:
A worm and a virus are similar in nature and how they are programmed to operate. However, unlike viruses, worms are independent and do not necessarily need to attach themselves to other programs. They spread replicate copies of themselves from one PC to another. Choosing option B is wrong because they are standalone and do not need to attach themselves to a host program too. Worms look for vulnerable systems that can be exploited and spread their wings from PC to PC found in a network. Thus, option D is correct. Worms do not necessary erase data. There are a few that can do that but not all.