We might expect to not find life around halo stars (“Population II” stars) because:
a) they are out of the plane of the galaxy and thus exposed to more cosmic rays (energetic nuclei)
b) these stars are all too hot and thus will expose any planets to too much ultraviolet radiation
c) these stars lack the heavy elements (“metals”) out of which life can form
d) these stars have existed too short a time for life to have evolved
e) the stars all pass too close to the central supermassive black hole in the Milky Way
I am stumped on this question, any ideas?