What is a characteristic of high explosives?

High explosives are characterized by their ability to sustain a reaction front that moves at or above the speed of sound, which is why this answer is correct. This swift propagation of the combustion wave means that high explosives can create a shock wave that leads to a more destructive and instantaneous reaction compared to low explosives, which typically burn rather than detonate.

This high-speed reaction is what distinguishes high explosives, allowing them to produce significant energy release over a very short period, creating the potential for substantial damage, as seen in military applications and demolition practices.

In contrast, the other options do not accurately describe the behavior of high explosives. For instance, the first option incorrectly implies that high explosives can only produce deflagration, which is more characteristic of low explosives. The requirement of a detonator for initiation can be true for many high explosives; however, not all require this. Finally, high explosives do create significant pressure changes as a result of the rapid reaction, further emphasizing their explosive nature rather than indicating a lack of pressure effects.