Which is the correct definition of the pathogens known as viruses?

Could you send me more information please???

I know this doesn't fit with what you are looking for on your assignment but I figured I would throw in some extra information for you just for fun. Viruses are tiny microscopic organisms that hide a nasty surprise. Sickness! When they get inside us that's when they start dealing hack on our poor bodies! Some viruses are deadly some are not. Some can take weeks to take full swing in making you sick some have symptoms that appear within just a day or two. It all depends on what virus you have.

Ithink it’s d. that should be correct.