You ___ react to any sudden and/or unexpected movements of drivers near you.

The correct choice emphasizes a guideline that is critical for safety while driving, particularly in environments where interactions with other vehicles can be unpredictable. The word "should" indicates a strong recommendation for drivers to be attentive and responsive to the actions of others on the road, especially when it comes to sudden or unexpected movements. This proactive approach can significantly reduce the risk of accidents, as it encourages vigilance and encourages drivers to maintain a safe distance, be prepared to react, and adjust their driving behavior according to the conditions around them.

In contrast, options that imply a lesser degree of obligation or urgency, such as "might" or "should not," do not convey the same level of responsibility that drivers have toward ensuring their own safety and the safety of others. Moreover, the use of "must" implies a legal requirement or an uncompromising obligation, which may not accurately reflect the flexibility of judgment that drivers should exercise based on the situation.