You're answer is going to be C.
The correct answer is the introduction
Thesis sentences for almost all types of texts are located in the introduction. Usually the exceptions where it's not are rare.
Answer:
FIrst of all, Choose the right theme for the Podcast.
Second, You should be Consistent.
Third, Make sure you Podcast is friendly and polite.
Fourth, Keep a good control over the Podcast.
Hopefully, it helps..
The answer would be "To splash"