Answer: option 3. 24m
Explanation:
concept to know: (a+b)²=a²+2ab+b²
(a-b)²=a²-2ab+b²
(2m+3)²-(2m-3)²
=(4m²+12m+9)-(4m²-12m+9) ⇔ Use the formula mentioned above
=4m²+12m+9-4m²+12m-9 ⇔ take off parentheses
=4m²-4m²+12m+12m+9-9 ⇔ move the like term together
=24m ⇔ combine like term
Hope this helps!! :)
Please let me know if you have any question