Studies of the Endomembrane System Often Involve the Use of a Protein

Studies of the endomembrane system often involve the use of a protein that can emit a green fluorescence (glow) . A researcher wants to make a video of cell behavior, so she initially labels the outer nuclear envelope of a cell with the fluorescent tag and records a video for several hours. Later, she sees that the tag is part of a transport vesicle very close to the plasma membrane.
-The ability to stain protein molecules with a fluorescent dye would most clearly allow researchers to go beyond what they could previously detect with a microscope by allowing them to

A) detect ribosome activity.
B) detect when DNA is replicating.
C) distinguish a prokaryote from a eukaryote.
D) determine whether a cell had cilia or flagella.