Answer:
-m^2 - 9m + 3 (the third one)
Step-by-step explanation:
separate the terms and group them with their equivalents (integers:inetgers, variables: variables, etc.) like so:
4m^2 & -5m^2 = -m^2
-8m & -m = -9m
12 & -9 = 3
add them all together to get the expression -m^2-9m+3
