How do I say 'As to why I chose this topic...'

Question

I have a highschool Japanese oral exam coming up in which we discuss a topic of my choosing, along with an accompanying image that relates to said topic. I have already memorised responses to many potential questions, but to maximise the use of what I have learned, how can I preemptively bring up a question for me to answer that I don't think the assessor will ask.

To be specific, the topic we are discussing are 'Manga Cafes in Japan'.

Two potential questions I expect the assessor to ask are 'Why did you choose this topic?' and 'Why did you choose this image?'

In the event that the assessor asks only one of these questions, I would like to be able to preempitavely bring up the next question.

Here is how I would like the exhange to go in English, along with what my current Japanese responses are:

Why did you choose this topic? (この　とピク　を　選びましたか）

I chose this topic because I like manga and I knew of manga cafes from the internet. I thought it was interesting, so I chose this topic. （私はまんがが好きでインタネットから漫画喫茶についてしりました。面白いと思いました。だからこのトピクを選びました。）

As to why I chose this image, (????)

There are various manga cafes in Japan, but this one is pretty and has a unique design. So I chose this image. （日本に色々な漫画喫茶がありますが、このしゃしんはきれいでディザインがユニークと思いますから、このしゃしんを選びました。）

This is a bit of an exhaustive post for such a simple question, but I hope it effectively conveys what I am trying to say.

ありがとうございます。

Answer 1

You can say:

1. この写真を選んだ理由ですが、...
2. なぜこの写真を選んだかですが、...

As to why I chose this image, ...

The first form may be easier. This が is not "but" but a particle used to give an introductory statement (see: this). The second form uses か, which forms an embedded question. This noun + ですが is a handy expression to define what you are talking about at the beginning of a sentence (it works more "globally" than the thematic-は). noun + だけど is a casual equivalent (see this for examples).

_{(By the way, your translation has a number of spelling mistakes, but we don't do bulk translation checks. Phrase requests are generally welcome, but please always try to provide your previous research on the phrase in question. Otherwise, your question may be closed.)}