The correct answer is B: At least one lanyard attached to the tower at all times. '100% tie-off' regarding tower safety means at least one lanyard attached to the tower at all times. This ensures you're always secured to the tower and can't fall. 100% tie-off is a critical tower safety requirement. It means you must always have at least one safety lanyard connected to the tower. When you need to move a lanyard to a higher point, you attach the second lanyard first, then remove the first. This way, you're never without a connection to the tower. This prevents falls if you slip or lose your grip. 100% tie-off is a fundamental safety rule for tower work - you must always be secured. This is why climbers use two lanyards - one stays attached while the other is moved.