Help with showing lack of a 'because' construct in translating the bolded sentence?


Two characters are having the following conversation:

> A:「あなたにも殺し屋になってもらうの。ツヴァイ」
>
> “You too will become a assassin. Zwei.”
>
> B:「馬鹿言うなよ……。なんで僕が、そんなことやらなきゃならないんだよ⁉」
>
> “Don’t say something so ridiculous……. Why me, why do I have to do that sort
> of thing!?”
>
> (TL note: reason why I went with 'have to do' instead of 'must' for やらなきゃなら
> is because 'have to do' in my mind gives a better sense of being forced to
> preform or do something than 'why must I do...').
>
> A:「 **生きるためよ** 」

I know that the final bit in Japanese is a relative-clause structure, with the
verb 生きる (example def: to live/to function) modifying the noun ため (example
definitions: good/benefit/result/etc). So far, the translations I've come up
with that are closest to the Japanese are the following two:

> a) You’ll get to live.
>
> (I'm doubtful of the above translation's representation of the relative
> clause in the original)
>
> b) Because you will live.
>
> (I'm also doubtful of my second translation as it uses the word 'because';
> although it seems to be more faithful to the relative clause structure in
> the original)

What I'm stumped on is how to represent the relative-clause structure without
using the word 'because' in English; because as far as I'm aware, there is no
'because' (other than a possible omitted one?) in the original Japanese. Which
translation is more accurate in comparison to the original, and what would be
a better possible translation that achieves both (1) and (2) of the TDLR
below?

**TDLR** : Context: Character A says something to which Character B asks a
'Why' question, Character A answers without a 'because' clause. Translator
(me) is stumped on how to show Character A's answer in English while (1)
remaining faithful to the Japanese relative-clause sentence structure, and (2)
not use the word 'because'.




This ため in 生きるため is a purpose marker, not a reason marker. The closest English
noun is "sake" as in "for safety's sake", but you can choose to use other
expressions that can express a purpose.

>   * 英語を勉強する **ため** (に)学校に行く  
>  to go to school **in order to** study English
>
>   * 安全 **のため** (に)ヘルメットを被る  
>  to wear an helmet for safety **'s sake**
>
>

Therefore this 生きるためよ is translated as "(It's) for (the sake of) your life" or
"In order to live". As you can probably see, this adverbial phrase perfectly
works as an answer to the question even without explicitly saying なぜなら
("because") or something.




This ため in 生きるため is a purpose marker, not a reason marker. The closest English
noun is "sake" as in "for safety's sake", but you can choose to use other
expressions that can express a purpose.

>   * 英語を勉強する **ため** (に)学校に行く  
>  to go to school **in order to** study English
>
>   * 安全 **のため** (に)ヘルメットを被る  
>  to wear an helmet for safety **'s sake**
>
>

Therefore this 生きるためよ is translated as "(It's) for (the sake of) your life" or
"In order to live". As you can probably see, this adverbial phrase perfectly
works as an answer to the question even without explicitly saying なぜなら
("because") or something.

