【正确答案】 B

【答案解析】The prime factors less than 10 are 2, 3, 5, and 7, so the product of any two of those cannot be correct. That eliminates choice A (the product of 2 and 3), C (the product of 2 and 5), D (the product of 2 and 7), and E (the product of 3 and 5). Since 9 is the product of 3 and 3, which are not distinct (or 1 and 9, which are not prime), B is the correct answer.