Which one of the following influenza is most deadly?

(A) H1N1 > Respiratory infection popularly known as SWINE FLU is caused by an influenza virus first recognized in spring 2009, near the end of the usual Northern Hemisphere flu season.> New virus, 2009 H1N1, spreads quickly and easily. A few months after the first cases were reported, rates of confirmed H1N1-related illness were increasing in almost all parts of the world. As a result, the World Health Organization declared the infection a global pandemic. That official designation remained in place for more than a year.