What does the following algorithm compute? The input n represents a natural number.

ALG$2($n$)$

if $($n$=1)$ return $1$

else return ALG$2($n$-1)+$n

a$.$ Sum of the first n natural numbers

b$.($n$-1)+$n

c$.$ None of the above

Which of the following is true regarding the algorithm mentioned above?

a$.$ ALG$2$ represents the fastest way for computing ALG$2($n$)$

b$.$ There is no way to write an iterative version of ALG$2$

c$.$ ALG$2$ can be rewritten so that it only contains a single return statement