x: boy, y: girl
R(x,y) means x loves y.
Ok. Question says
For all boys & girls in the world, a boy loves a girl means that girl loves him too..
It is true sometimes too.
Hence satisfiable.
Negation of it is also satisfiable.
think logically or negate it mathematically then put this example.. In some cases these will be true.
Hence B is the answer.