In the video, "immigrant workers—where the hazardous jobs are", global migration was said to have dramatically increased over the past decade, with numbers over 200 million transnational and over 1 billion total migrants globally.

Which of these is a drawback of using natural gas? a. it is fairly safe for use in homes. b. it burns more cleanly than crude oil products. c. scientists have developed new ways of extracting it. d. during its extraction, groundwater can be contaminated.