Part A) the first and the third answer are equivalent because.
n+n+n+n+2= 4n+2 which is the same as the third answer.
Part B) 2 and 4 are not equivalent because
2) n+n+n+2= 3n+2
4) 2n+2n+2n= 6n
as we can see they are not the same. Therefore they are not equivalent.
hope this helps