Which of the following statements are true about spatial alarms based on the material we have covered? $($Note: the description need not be a complete definition of the term; it merely must be an accurate statement about the term.$)$

Group of answer choices

$($A$)$ Spatial alarms are less useful and thus have not been deployed as a new location based service.

$($B$)$ The naive periodic time interval based processing of spatial alarms is both cost and energy inefficient.

$($C$)$ The safe region based approach for evaluating spatial alarms is more resource and energy efficient than the periodic time interval based approach.

$($D$)$ Road network distance can capture the real travel time of a mobile user moving on the road more accurately compared to using Euclidian distance.

$($E$)$ The decision of the time interval for periodic spatial alarm processing only impacts on whether or not the evaluation of some alarms will be missed.