Answer:
I believe it would be 3n^2 (last option)
Explanation:
By definition;
monomial- one term
coefficient- the number in front of a variable
(in this case, without the squared power, it would look something along the lines of "3n", where the 3 is the coefficient and the "n" is the variable.)
sooooooo,
even without the "2nd degree" we can just use the system of elimination and cross out the answers that don't consist of one number, and that don't have a coefficient of 3.
I hope this answer was helpful, please let me know if you got it correct. :)