Question about use of セリフ in Yotsuba vol 1


I was struggling with this part of Yotsuba vol1 and couldn't find any other
questions on it so I thought I would post here to make sure I am understanding
this right.

The sentence reads

> お？どこでおぼえたそのセリフ

And is a response from Jumbo after Yotsuba comments on how much he has grown
since she last saw him.

Just from looking at an English version of the comic, I know that he is saying
something long the lines of:

> Hah. Where did you remember that phrase from?

I know `どこ` means `where`, and from [Jisho](http://jisho.org/search/remember)
it looks like `おぼえた` comes from `覚える` (to remember).

The last part, `セリフ` has a few translations on Jisho:

  1. **セリフ** - serif (as in font/typography)
  2. **台詞** - speech; words; one's lines; remarks (​Usually written using kana alone)
  3. **台詞回し** - theatrical elocution​

of which option 2 seems to make the most sense.

Does this all seem correct, and if so is there any reason why the last word is
written in katakana?

[![enter image description
here](https://i.stack.imgur.com/hCxUz.png)](https://i.stack.imgur.com/hCxUz.png)




> Does this all seem correct

Yes, it not only seems, it is correct.

> if so is there any reason why the last word is written in katakana?

No. No other reason except for: " _usually written using kana_ ".

Most likely because one or more predominant dictionaries of the Japanese
language included that form as a referential, or some style guide defined this
form as preferred.




> Does this all seem correct

Yes, it not only seems, it is correct.

> if so is there any reason why the last word is written in katakana?

No. No other reason except for: " _usually written using kana_ ".

Most likely because one or more predominant dictionaries of the Japanese
language included that form as a referential, or some style guide defined this
form as preferred.

