I'm having trouble understanding the best way to respond to someone asking "why".
My study guide advised,
To answer the question with "why", make a statement sentence that indicates the reason and add からです at the end,
A: どうして昼ご飯を食べなかったんですか B: ダイエットをしているからです
Feeling like it couldn't possibly be that simple, I went looking to see if anyone had explained things in more detail.
However, nearly every sentence with から I found are sentences that describe both the cause and response, seemingly not as a response to a "why" question, such as this sentence taken from another post
あのラーメン屋は人を待たせるから、行かないことにした。
I haven't been able to find much at all on からです in direct response to a question, as it was in my book's example.
I figured the most likely reason for this was either
A. からです is a nonstandard approach and my book is weird, or
B. I've missed something.
Unfortunately, B prompted me to wonder if some of these descriptions actually were a direct response that I was misunderstanding.
So, while I was searching for something like
A： どうして外に行かなかったんですか
B： 雨が降っていたからです
People were actually saying
A： どうして外に行かなかったんですか
B： 雨が降っていたから、外に行きませんでした
In short, is something like "ダイエットをしているからです" actually a standard way to give a reason in response to a question? If not, what would be more appropriate?
Any other ways to give a reason are welcome, because nuance is neat.
