The answer would be A.
Eukaryotes contain a membrane bound nucleus where they store all their genetic material such as DNA. DNA in prokaryotes is free floating within the cytoplasm.
C. All living organisms likely originated from a common ancestor ( because all living organisms store genetic information through DNA and RNA. These are linked to a shared ancestry and is how organisms evolve using new genes )
Skin,mouth and sometimes they have gills which they absorb oxygen
It should be based on the principles of immunology to understand this phenomenon: the immune system produces antibodies against an antigen that it does not possess
The AB group contains the A and B antigens on the red blood cells, so it can not produce anti-A antibodies or anti-B antibodies since it already possesses antigen A and B (otherwise it will develop autoimmunity).
Yes earth can make ferromagnetic true