Respuesta :
The sentence from the source which best supports the reason "texting should be banned because it impais drivers" is the following one:
4- Some studies suggest that texting doubles a driver’s reaction time to roadway hazards.
That is the best reason, since it is not only about making drivers distracted, as in number 3, but it is actually about a change in the number of seconds it will take a driver to react when facing a roadway hazard (it will take longer). When it comes to driving, a few seconds make the whole difference (actually, the difference between life and death) and if texting impairs drivers it should be banned indeed.