Which phrase most the reader conclude that the author’s purpose is to persuade?
"what? i am to cultivate my mind in the street, on the platform, in the train, and in the crowded street again? ” precisely. nothing simpler!
“cultivate my mind”
“on the platform”
“crowded street”
“nothing simpler

The answer is:  [D]:  "Nothing simpler" .

  Note:  This phrase is used after the word, "Precisely."  Furthermore, the word, "Nothing",  is an "absolute" word.  
   
       Given the fact this phrase, "Nothing simpler!",  is used after the word, "Precisely"—as a "single direct word" in a oral quotation (and as a single direct phrase as "repetition") — suggests the author's purpose to persuade (as opposed to the other answer choices given).