Someone please help me, I'll give you brainliest!!! (For Dark Paradox)

[tex]\qquad\qquad\huge\underline{{\sf Answer}}[/tex]
If two similar waves are traveling in the same medium, then they have same wave velocity. so we can infer that
[tex]\qquad \tt \dashrightarrow \:v_A = v_B[/tex]
Now, as per the formula ~ we know that :
[tex]\qquad \sf \dashrightarrow \:v = \lambda \cdot f [/tex]
Now, we can write it as :
[tex]\qquad \sf \dashrightarrow \: \lambda_A \cdot f_A = \lambda _B \cdot f_B[/tex]
And it's also given that frequency of wave A is 3 times that of frequency of wave B.
So, let's add the relation to our equation ~
[tex]\qquad \sf \dashrightarrow \: \lambda_A \cdot3f_B = \lambda _B \cdot f_B[/tex]
[tex]\qquad \sf \dashrightarrow \: \lambda_A \cdot3= \lambda _B[/tex]
[tex]\qquad \sf \dashrightarrow \: λ_A = \frac{1}{3} λ_B[/tex]
So, choice C is correct ~