Help to understand material implication This question comes from from my algebra paper:
$(p \rightarrow q)$ is logically equivalent to ... (then four options are given). 
The module states that the correct option is $(\sim p \lor q)$. That is: 

$$(p\rightarrow q) \iff (\sim p \lor q )$$

but I could not understand this problem or the solution. Could anybody help me?

Given the material implication X, 

X: if p is true, then q is true

the possibilities are: