main question is to what "that" refers?
is it referring to AM-1 or satellites?
I think it is referring to satellites, because all the satellites are part of effort and not just AM-1, so that eliminates A and B.
C makes " part of 15 years effort of subjecting how Earthâ€™s atmosphere .. " modifying whole main clause , so this is not correct.
this left us with D & E.
in D -> "that are part of an effort for 15 years that has subjected the interactions" -> second "that" refers to effort ??, so does it means effort has subjected the interactions? I find this option as wordy and ambiguous.
in E -> " that are part of a 15-year effort to subject the interactions" -> clear meaning compare to D.
So, for me its E
the Battle continues ..