Which of the following best describes the difference between a virus and a worm? $\_\_\_\_\_$

a$.$

A worm is malicious software that requires a host file to spread itself, whereas a virus is malicious software that does not require a host file to spread itself.

b$.$

A virus is malicious software that attaches itself to executable files, whereas a worm is malicious software that attaches itself to an image file.

c$.$

There is no difference between a virus and a worm.

d$.$

A virus is malicious software that requires a host file to spread itself, whereas a worm is malicious software that does not require a host file to spread itself.