The correct answer is C. Rajan strongly wished that he had been a child again.
The sentence “O that I were a child again!” is an expression of strong desire. It is a wish that Rajan could be a child again. The use of the word “O” indicates that Rajan is expressing a strong emotion, such as longing or regret. The word “were” is the past subjunctive, which is used to express wishes or hypothetical situations. The sentence can be paraphrased as “I wish I were a child again.”
Option A is incorrect because Rajan is not expressing wonder. He is expressing a wish.
Option B is incorrect because Rajan is not expressing a question. He is expressing a wish.
Option D is incorrect because Rajan is not praying. He is expressing a wish.