B) to convince Sterne to write about slavery
Step-by-step explanation:
The paragraph eulogizes Sterne's influence all over the world as a man of letters and goes into his unquestioned wisdom.
This is followed by an appeal rather direct that if he handles the subject of slavery it will ease the pain of many people in the west Indies. Then he appeals to the sense of charity in the mind of Stern.
This is followed by a final salutation that calls Sterne universally admired. Clearly this is a plea for hep asking Sterne to bring attention to slavery using his platform.