The correct answer is A. 25413.
Rahul is poor, yet he is happy. This is because Rahul is a kind and generous person who is always willing to help others. He is also very optimistic and believes that things will always work out in the end. Even though he may not have much money, he is rich in love and happiness.
Option B, 24315, is incorrect because it suggests that Rahul is happy because he is poor. This is not the case, as Rahul is happy despite his poverty.
Option C, 23541, is incorrect because it suggests that Rahul is poor because he is not happy. This is also not the case, as Rahul is happy despite his poverty.
Option D, 21453, is incorrect because it suggests that Rahul is not happy because he is poor. This is not the case, as Rahul is happy despite his poverty.