P is the brother of Q and R. S is R's mother. T is P's father. How many of the following statements are definitely true? I. S and T are a couple. II. Q is T's son. III. T is Q's father. IV. S is P's mother. V. R is T's daughter. VI. P is S's son. Select the correct answer using the code given below:

To solve this, we first establish the family relationships based on the given information: 1. P is the brother of Q and R. This means P, Q, and R are siblings. P is male. 2. S is Rs mother. Since they are siblings, S is the mother of P, Q, and R. 3. T is Ps father. Since they are siblings, T is the father of P, Q, and R. Now, let us evaluate the statements: I. S and T are a couple: Definitely true. S is the mother and T is the father of the same children. II. Q is Ts son: Not definitely true. We know Q is Ts child, but we do not know Qs gender. Q could be a son or a daughter. III. T is Qs father: Definitely true. Since T is the father of P, he is also the father of Ps sibling Q. IV. S is Ps mother: Definitely true. Since S is the mother of R, she is also the mother of Rs sibling P. V. R is Ts daughter: Not definitely true. We know R is Ts child, but we do not know Rs gender. R could be a son or a daughter. VI. P is Ss son: Definitely true. We know P is male (brother) and S is his mother. Statements I, III, IV, and VI are definitely true. Statements II and V are uncertain due to unknown genders. Since exactly four statements are definitely true, the correct answer is C.