second xs $=$ head $($tail xs$)$

$($a$)(10$ points$).$ What is the type of second? Note: that type has a formal meaning in Haskell,

that is$,$ there is only one correct $($and very precise$)$ answer.

$($b$)(10$ points$).$ Explain why second has the type that it has. That is$,$ why does chaining tail and head together $($or composing them$)$ in the function definition above give rise to the type that second has?