Complex sentence: The QB makes the decision whether to give the ball to the fullback (FB) or to keep the ball based his read of the defense, if the QB keeps the ball, he has a third option to hand the ball off to the tailback.
Split into simpler sentences: The QB makes the decision whether to give the ball to the fullback (FB) or, based on his read of the defense, to keep the ball. If the QB does choose to keep the ball after the initial snap, he still retains the option of employing a third option; handing the ball off to the tailback.