Final answer:
The age of Sergio's cousin, Ralph, cannot be determined based on the given information.
Step-by-step explanation:
The question is asking about the age of Sergio's cousin, Ralph. Unfortunately, there is no information provided in the question that directly states Ralph's age. Therefore, it is impossible to determine how old Ralph is based on the given information. As a result, none of the answer choices A) 12 years old, B) 15 years old, C) 18 years old, or D) 20 years old can be confirmed as the correct answer.