Normal Form Theorem $($Kleene$,1943)$:

"Giten a partial recursive function $(x_1,$dots,$x_n),$ there is a number $e$ such that

$(x_1,$dots,$x_n)$~~$U(y{T}_n(e,x_1,$dots,$x_n,y)).$

Select all the true statements regarding Kleene's normal form theorem:

The value of $y{T}_n(e,x_1,$dots,$x_n,y)$ is a natural number.

For all function $,$ the value of $y{T}_n(e,x_1,$dots,$x_n,y)$ is defined

$U$ can be considered as a form of encoding function

$y{T}_n(e,x_1,$dots,$x_n,y)$ can be considered as a form of decoding function

$y{T}_n(e,x_1,$dots,$x_{n}y)$ can be considered as a form of encoding function

Every recursive functions can be attributed a unique encoding number e

$T_n$ is a primitive recursive predicate

$U$ can be considered as a form of decoding function

$y{T}_n(e,x_1,$dots,$x_n,y)$ is a primitive recursive function

$U$ is a primitive recursive predicate

Every primitive recursive functions can be attributed a unique encoding number $e$