Nina has the flu and a high fever. her immune system is exhibiting what line of defence

A high fever - that is, raising the temperature to make the body a less pleasant place for viruses and bacteria - is the first line of defence - the first thing that the body does to fight infections. It is a part of the innate immune responce - we don't have to "learn" it, as in the cases of some other immunological responces to specific bacteria and viruses.

An advantage of an mri over ct scan is d. it produces better images of hard tissues. hope this : )