Which of these functions are odd?
A. $f(x)=\csc(x^2)$
B. $f(x)=2\sin(x)\cos(x)$
C. $f(x)=\cos(2x)$
D. $f(t)=2+\tan(t)$
E. $f(t)=\sec^2(t)-1$
F. $f(x)=\sin(2x)$