2. outlive their usefulness:become no longer useful 。 So it's not necessary to support “without hampering people’s ability to report a fire”。Choice A cogently support "Removing the boxes will reduce the number of prank calls".
1, considerably less than 5$, which leaves a possibility that even only a small portion of workers get paid less than minimum wage, the effect of raising minimum wage from 5 to 5.5 could be phenomenal. therefore, i reckon b should be the answer
2, choice a,whether the fire department can trace the phone calls made from private phone , removing the alarm boxes reduces the prank calls anyway,
in choice c, if the alarm boxes are more effective than the private phone calls, we cant conclude that removing the alarm boxes wouldnt hamper the ability to report a fire.