Read the passage below and then choose the best answer to each question. Answer the questions on the basis of what is stated or implied in the passage.
Passage
Today's ubiquitous red-yellow-green electric traffic light, familiar to drivers worldwide, had its origins in train signals from the 1800s. These early signals all used red to signify "stop," but the choice and arrangement of the other two colors would surprise today's drivers: green was the color for "caution," and white was the color for "go." However, white proved to be a poor choice, because the red and green lights train engineers saw were produced by red and green filters covering white light bulbs (the "go" light had a clear filter). If a filter was broken or missing, the signal would appear as white and engineers might mistake "stop" or "caution" for "go," especially at night.