Can the defense shift according to the rules?

The defense is allowed to shift as long as they adhere to certain rules that prevent causing a false start. A shift occurs when players change their positions on the field before the snap. The key aspect is that defensive players must be careful not to make movements that simulate a snap count or cause offensive players to jump, which would lead to a false start penalty. By allowing a shift without causing a false start, defensive teams can adapt their formation in response to offensive alignments and strategies.

The other options do not align with the rules governing shifts. The notion that only offensive players can shift is incorrect, as defensive players can also shift, provided they follow the relevant rules. Additionally, stating that the defense can shift at any time does not take into account the requirement to avoid causing a false start, which is critical for maintaining the integrity of the play. Lastly, while being set before the snap is necessary for offensive players, it does not restrict defensive shifts as long as they comply with the false start rule. This nuance is crucial for understanding defensive strategies in football.