Answer:
C.
![3x^2y](https://img.qammunity.org/2020/formulas/mathematics/middle-school/5kt1q7mpys1hymtwphgdpwpydi9eu4cvs3.png)
Explanation:
Given the trinomial
![18x^2y-9x^2y^2+6x^3y](https://img.qammunity.org/2020/formulas/mathematics/middle-school/y3mruvrkvjxealbin92o9jolfsb2xfhtj5.png)
consisting of three terms.
Find the greatest common factor of numbers:
![18=2\cdot 3\cdot 3\\ \\9=3\cdot 3\\ \\6=2\cdot 3\\ \\GCF(18,9,6)=3](https://img.qammunity.org/2020/formulas/mathematics/middle-school/2mexl5x9tz87c3movb2d7g03ono3vhr9ev.png)
Find the greatest common factor of powers x:
![x^2=x\cdot x\\ \\x^3=x\cdot x\cdot x\\ \\GCF(x^2,x^3)=x\cdot x=x^2](https://img.qammunity.org/2020/formulas/mathematics/middle-school/q0i1sakfsapfpfoz4plg5kyuyngoys06ld.png)
Find the greatest common factor of powers y:
![y=y\\ \\y^2=y\cdot y\\ \\GCF(y,y^2)=y](https://img.qammunity.org/2020/formulas/mathematics/middle-school/nx5qnwh0dhqgpui1p5vl44e8jvxt1my8to.png)
Thus, the greatest common factor of the whole terms is
![3\cdot x^2\cdot y=3x^2y](https://img.qammunity.org/2020/formulas/mathematics/middle-school/kmxnk0ht2b3ho3t6gjdqfjkb3y3v5xgdr6.png)