Twilio account setup query

I am setting up my Twilio account so while selecting the API key which key type should I select whether Standard API key or Master API key? also even after the account is verified while purchasing the dummy phone number it is asking to verify the account

You should select Master API Key.

@shamalpatil1998 Will that charge me any extra bucks?

NO, nothing like that happen. its free

Thanks. I have successfully created a Twilio account