1. what is the difference between a specific and a nonspecific defense?

  A specific defense mechanism is just that it is specific against a particular antigen. An antibody is an example of a specific defense. 

A nonspecific defense mechanism works against any foreign "invader." Skin is considered a non-specific defense. The lysozyme in tears will destroy any bacteria.

Ithink option a is correct because you cannot donate a different blood group than yours because it won't match.option a says betsy can donate to mark. they have the same blood group so donation can happen.