Which of the Following Are True About Every Periodic Function $f$

Multiple Choice

Which of the following are true about every periodic function $f$ with period 3 and amplitude 3 ?

A) $f(x+9) =f(x+6)$
B) $f(x) =-f(-x)$
C) $f(x-3) =f(x+12)$
D) $|f(x+3) |=|f(x+6) |=3$