6. What’s the answer to this question

Answer:
D. 6x²y³
Step-by-step explanation:
Like GCF in numbers, 3x²y should evenly divide into 3x⁴y and the other monomial, and is the largest one to do so in both.
So, we have to find a monomial that 3x²y divides evenly into, and that 3x²y is the largest monomial that can evenly divide into it and 3x⁴y.
A can not work, because 3x²y does not divide evenly into 3xy².
B and C can not work, because the GCF in those two and 3x⁴y will have a larger power of x.
The only one left is D. And looking at it shows that it all checks out.