I need some help with understanding if a grammar is $LL(1)$ or not.

$$

begin{align}

S rightarrow AB\

A rightarrow a mid varepsilon \

B rightarrow bCd\

C rightarrow c mid varepsilon

end{align}

$$

I have computed the first and follow sets and I’ve tried to use $LL(1)$ definition, but I don’t know how to answer it.

Thanks in advance.