<prompt> Immunity may be natural or acquired. Which of the following best describes acquired immunity?Increase in C-reactive protein CRPPresence of natural killer NK cellsComplement cascadeMaternal transfer of antibody  <response>: Natural immunity is nonspecific. The description of natural immune functions described are not specific for a certain antigen. For example, certain proteins such as C-reactive protein CRP are acute-phase reactants. While elevated CRP is seen in infection, it is not disease-specific. Maternal transfer of antibody, however, is passive but still confers specific immunity. It is termed acquired immunity. 