O positive is the most common blood type and most likely to be transfused.
O negative donors are the “Universal Donor.” People with O negative blood are universal red blood cell donors. This means that their red blood cells can be transfused to any blood type.
If you're asking this question in terms of Literature, the film that is most famous for its use of synchronized sound is the jazz singer the jazz singer triggered the talking-picture revolution A year after the release of few different films, Hollywood recognized the importance of the jazz singer with regard to the motion picture history by honoring the film with an special award. :) Hope I helped!
A) gravitropism is how they "know"
I think its C.
I hope this helps and please do correct me if im wrong.