Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Transport makes up a quarter of the world’s carbon emissions, with buses producing an average of 822 grams of carbon dioxide per kilometer. This is one of the leading factors inspiring the innovation of electric transport and the rise of the electric bus, or e-bus.
Electric buses can charge throughout their journey with stations at every bus stop, enabling automatic charging whenever the buses pick up or unload passengers. Named “Opportunity Charging” due to the e-bus’s ability to charge whenever it is near a station, this method is more energy-efficient and cost-effective, removing the need for individual buses to leave their routes to refuel at petrol stations.
Generating the required energy through battery charging at stations is obviously much better for the planet, but what about the people who will occupy the seats inside? These buses do not only benefit to the environment, but they can also make your commute a more pleasant experience, as the e-bus makes far less noise and provides a much smoother journey than older petrol-fueled buses with no engine vibration.
The potential for bus routes could also be much greater. A silent electric vehicle opens up possibilities for new bus stop locations. Soon you may not have to step outside a shopping centre to catch the bus, as the smooth and quiet rides could stop indoors with minimal commotion.

Câu hỏi

The word “they” in paragraph 3 refers to ______.