Books: Nintendo Games Secrets - The Best of How to Win at Nintendo Games
To select any of the 21 missions in the game, wait until the
"Press Start Button" message appears, press and hold A, B, and Down,
and then press Start. This changes your score to 11. Use Buttons A
and B to change your score. The first number in the score (ten digit)
is the Round number and the second number (ones digit is the Stage
number. Press Start to begin the game once you have chosen the right
Stage and Round.