I need answer of allQuestion $8$

Consider the sequence $a$:$NN$ defined by $a_n=4n-1.$ What is the domain and codomain of $a_n?$

Rational numbers, rational numbers

Integers, integers

Real numbers, real numbers

Natural numbers, natural numbers

Question $9$

Which best describes an onto function?

A function that assigns multiple outputs to every input

A function that assigns a single output to every input

A function that assigns one output to multiple inputs

A function that maps an input to every element of the codomain

Question $10$

$2$ pts

Define $x=\{a,b,c,d\}$ and $Y=\{a,b,c,d,e,f\}.$

Let $f$:$xY$ be a function defined by $f=\{(x,x)|xinx\}.$

Is $f$ one to one?

Yes because every output has a corresponding input

Yes because no two inputs have the same output

No because an output does not have a corresponding input

No because two inputs have the same output