In the 1990s astronomers carried through exhaustive lensing experiments involving the study of millions of stars in the galactic central areas and in the Magellanic Clouds to search for dark objects whose masses would cause lensed brightenings of background stars.
i.            In the 1990s astronomers carried off
ii.            In the 1990s astronomers carried in
iii.            In the 1990s astronomers carried out