Both ways of inducing active immunity (vaccines and direct environmental exposure to an antigen) will ultimately result in the production of antibodies. which of the five classes of antibodies is the first to be secreted during the primary response after the initial exposure to the antigen?

mountains can affect the climate of nearby lands. in some areas, mountains block rain, so that one side of a mountain range may be rainy and the other side may be a desert. much of airborne moisture falls as rain on the windward side of mountains.

explanation:

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.