An Extreme Ultrviolet imager telescope is used to observe the sun and corona.it has four filters which are sensitive to different wavelenghts of UV radiation.These are:

Question

filter:
17.1nm
19.5nm
28.4nm
30.4nm

Question:
which filters are most likely to be of most use in mapping coronal holes and why?

which filter is most likely to be of most use in mapping the solar transition region?

explain why the sequence of filters 17.1, 19.5 and 28.4 nm represent a sequence of incresing temperture of emitting regions

thank you very much