I think the answer is a but I am not for sure
You can't usually just use a single spectrum line to confirm the identity of an element because there are cases that the emission line id not clearly defined. When the emission line is very weak compared to surrounding noise, in which case the more datapoints you have to build up confidence for the existence of a particular emission spectra, the better.
More the number of turns, more will be the magnetic field produced.
Hence wire A will have magnetic field greater than wire B.
Hope this helps!
Put the mixture in water, the pebbles will sink, the pepper will float, and the sugar will dissolve