The correct option is E I and III only
Option D, representing nightingales and mowers, is correct. The speaker in the poem describes the glowworms providing assistance to the nightingales who stay awake long into the night because of their light, and the mowers who lose their aim without being guided by them. Because the poem suggests both of them being affected, Options A and C are incorrect, representing only each of these. Option B is incorrect because the statement mentions the glowworm assisting the princes, whereas the poem doesn't support this inference. Option E, enumerating all the three options is incorrect.