help I had got these answers incorrect and want to know what is the right answer and why

Given the ML function definition, fun mult x:int y:int z:int x*y*2; Which of the following is the type of the function in ML type notation? int - int - int - int int + int intint O intint int intint O int-- Ant - int O int-int Osnt intint Given the following ML code snippet: map (fn (a, b) => (b, a)) {(1,2), (3,4) 1: What is the value and type of it? val it - 13,7): int list val it in: int intint Oval it - 12,1),(4,3): int int lot Consider the following ML computation: (fn X => x) (fn x => x+1); What is the value and type for ML's internal variable? val it = fn: int -> int val it = fn : int val it = 1 : int val it = fn : int * int -> int