Question

streetlights became easier to reach. people stopped respecting lamplighters. cities began using electric lights. gas lamps caused more serious injuries. lamplighters jobs disappeared. effect cause ?

Explanation:

To determine the cause of lamplighters' jobs disappearing, we analyze the options. The effect is the disappearance of lamplighters' jobs. A cause should logically lead to this effect. "Cities began using electric lights" (third option on the left) is a technological change that would replace gas lamps (and thus the need for lamplighters), making their jobs obsolete. Other options like streetlights being easier to reach or people stopping respecting lamplighters don't directly relate to the job disappearance, and gas lamps causing injuries is not a direct cause for job elimination compared to the adoption of electric lights.

Answer:

Cities began using electric lights. (The third option from the top on the left - hand side of the image)