To answer this question, we need to have some knowledge about the movie "Kal Ho Naa Ho" and its storyline. In the movie, Shah Rukh Khan's character, Aman, shares a mantra to woo a girl. The correct answer is option C) "Che din ladki in."
Option A) Saat din ladki in - This option is incorrect because the correct mantra is not "Saat din ladki in."
Option B) Ek din ladki in - This option is incorrect because the correct mantra is not "Ek din ladki in."
Option C) Che din ladki in - This option is correct because Aman's mantra to woo a girl in the movie is "Che din ladki in."
Option D) Do din ladki in - This option is incorrect because the correct mantra is not "Do din ladki in."
Therefore, the correct answer is option C) Che din ladki in. This option is correct because it corresponds to the mantra shared by Shah Rukh Khan's character in the movie "Kal Ho Naa Ho."