Answer: 3pi (choice C)
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Step-by-step explanation:
I'm assuming you meant to say
y = (3/2)*tan( (1/3)x )
If so, then that equation is in the form
y = A*tan(Bx)
The B coefficient is B = 1/3 and it directly ties together to the period T.
T = pi/B
T = pi/(1/3)
T = pi*(3/1)
T = 3pi .... answer is choice C
Side note: This formula only works for tangent and cotangent functions.