You are given the country in question in three different sizes. You must choose the letter corresponding to the square with the correctly scaled country when compared to the reference country in the top left square.
Country sizes are based on their true size, as seen on a globe, and not on their Mercator projections.
In order to create a playlist on Sporcle, you need to verify the email address you used during registration. Go to your Sporcle Settings to finish the process.