The sentence "like a boil that can never be cured as long as it is covered up but must be opened with all its pus-flowing ugliness to the natural medicines of air and light, injustice must likewise be exposed" communicates a(n) tone. (5 points)

The sentence given above communicates A MATTER OF FACT TONE.
A matter of fact tone is one which expresses an opinion about a matter in an unemotional and straight forward way.
In the statement given above, the author prescribed the manner in which injustice should be treated in a dispassionate and straight forward manner without mincing words.