The scientific team using the Dark Energy Spectroscopic Instrument (DESI) to conduct a cosmological survey, which has generated the largest 3D map of our universe to date, plans to observe roughly 50 million celestial objects. Mounted on a telescope in Arizona, ____
Which choice completes the text so that it conforms to the conventions of Standard English?
Explanation
Context: The opening modifier is "Mounted on a telescope in Arizona." Whatever noun follows the comma must be the thing that is mounted—the instrument.
Answer: D) this remarkable instrument can measure 5,000 galaxies simultaneously, ...
Why? Placing "this remarkable instrument" right after the modifier makes DESI the mounted object, which is the only sensible reading.
Traps:
- A) the distribution of matter → a distribution can't be mounted on a telescope.
- B) researchers → the scientists aren't mounted on the telescope.
- C) 5,000 galaxies → the galaxies are being observed, not mounted.