The correct answer is 1) best defense.
Complete the following sentence: your attitude is your best defense.
When driving your car, you have t be 100% focused on the wheel and what is in front of you. Driving is a serious business. Your attitude is your best defense. Don't you ever show overconfident and think that you drive very well because that attitude is going to make you be distracted. Drive carefully to save your life and other lives. And never drink and drive. Ever.