What are the three basic components of a modern astronomical instrument? describe each in one to two sentences?

1. The telescope which is an instrument that collect electromagnetic radiation like visible light, radio waves, etc.

2. The spectrometer which is an instrument that uses the color (wavelengths) to categorize to measure the spectrum of celestial objects.

3.  The detector is an instrument that can be set up to recognize a specific color (wavelength) of the spectrum and record the observations.

it is either c or d and i know for sure it is not a or b

i need