can someone pls help with this? i’ll give brainliest :)

Answer:
D (I think)
Step-by-step explanation:
I used a right triangle calculator and that was the answer
Below is the process the calculator did, hope it helps.
[tex]c = \sqrt{a^{2} +b^{2}[/tex]
[tex]\sqrt{12^{2} + 9^{2} } = 15[/tex]