(a) The fundamental period is $2 \pi / 2 \pi=1.$
(b) The fundamental period is $2 \pi /(4 / L)=\frac{1}{2} \pi L.$
(c) The fundamental period of $\sin x+\sin 2 x$ is $2 \pi.$
(d) The fundamental period of $\sin 2 x+\cos 4 x$ is $2 \pi / 2=\pi.$
(e) The fundamental period of $\sin 3 x+\cos 4 x$ is $2 \pi$ since the smallest integer multiples of $2 \pi / 3$ and $2 \pi / 4=\pi / 2$ that are equal are 3 and $4,$ respectively.
(f) The fundamental period of $f(x)$ is $2 \pi /(n \pi / p)=2 p / n$.