Answer:
B). is really really hard, yo.
Step-by-step explanation:
The Tone is described as the approach or attitude adopted by the author towards a specific subject matter. It allows him/her to create the desired mood and offer a perspective to the readers to read or feel the text accordingly.
In the given paragraph, the author adopts a sincere and formal tone and the phrase 'is really really hard, yo' does not match the seriousness of the passage. This phrase is quite informal(as reflected by the repetition of 'really' and use of word 'yo') which is breaking the sincerity of the tone. The other options maintain the depth and formality of the approach adopted by the author. Thus, option B is the correct answer.