Final answer:
A triangle cannot be formed with side lengths 3 in, 5 in, and 9 in, because the sum of the two smaller sides is less than the longest side.
Step-by-step explanation:
A triangle can be formed with side lengths 3 in, 5 in, and 9 in. To determine if the student is correct, we need to check if the sum of the two smaller sides is greater than the longest side. In this case, 3 + 5 is less than 9, which means the student is incorrect. The correct answer is D) No, because 3 + 5 < 9.