AHHHH I GOTTA STOP POSTING SO LATE.
I mean idc though.
Astronomers rely on powerful telescopes to collect faint light from distant galaxies and measure how that light changes over time. _____ some instruments are so sensitive that they can detect slight variations in brightness caused by a planet passing in front of a faraway star.
A) Specifically,
B) Otherwise,
C) In other words,
D) By contrast,