Which of the following recursive procedures computes na$,$ where n is a positive integer and a is a real number?

$1.$ procedure mult$($a: real number, n: positive integer$)$

if n $>0$ then

mult$($a$,$n$)$ : $=$ a

else

mult$($a$,$n$)$ : $=$ a $+$ mult$($a$,$n $1)$

$2.$ procedure mult$($a: real number, n: positive integer$)$

if n $=1$ then

mult$($a$,$n$)$ : $=$ a

else

mult$($a$,$n$)$ : $=$ a $+$ mult$($a$,$n $1)$

$3.$ procedure mult$($a: real number, n: positive integer$)$

if n $=1$ then

mult$($a$,$n$)$ : $=$ a

else

mult$($a$,$n$)$ : $=$ mult$($a$,$n $1)$

$4.$ None of the above