Option D is the correct answer. (A), (B) and (D) are written in incorrect English.

Statement A: The absence of "the" before "king" makes this sentence grammatically incorrect. In standard English, when referring to a unique title or role like "king" in this context, the definite article "the" is required to indicate specificity. The correct sentence would be: "The lion is the king of beasts" or "The lion is the king of the beasts".

Statement B: Similar to (A), the phrase "queen of flowers" lacks the definite article "the" before "queen." The correct sentence would be: "The rose is the queen of flowers" or "The rose is the queen of the flowers."

Statement C: This is a well-known proverb and is grammatically correct as written. 

Statement D: The sentence uses the indefinite article "a" before "boy," which is incorrect in this context. When introducing a specific noun like "boy" with a restrictive relative clause ("I told you about"), the definite article "the" is required to indicate that the boy is a specific individual being referenced. The correct sentence would be: "This is the boy I told you about."