Adriver in a nearby lane that's tailgating a car ahead and to your side might be preparing to
a. slow down rapidly
b. cut in front of you
c. activate its hazard lights
d. warn you of an upcoming hazard

I believe the answer you're looking for is B "Cut in front of you". When someone needs over into the next lane but there is someone in that lane blocking them, they will often go as close to the car in front of them in order to make room for their car in front of yours. That's why people get pulled over for cutting you off since it's super dangerous. Hope this helps!