According to the Environmental Protection Agency (EPA), which one of the following is the largest source of sulphur dioxide emissions ?

States that sulphur dioxide (SO2) is one of the main gases producing acid rain and that the major sources are burning of fossil fuel and industrial processes.

A student could use this general rule plus sector-level SO2 data (e.g., power plants vs. transportation) to judge whether locomotives (a transportation sub‑sector) are likely the largest source.

Lists combustion of fossil fuels for electricity and for transportation as main sources of emissions, implying transportation is a contributor but separate from electricity/industry.

Compare relative emissions of the electricity sector (thermal power) and the transportation sector to see if the transport subsector 'locomotives' could dominate national SO2 emissions.

Specifies SO2 originates from volcanic eruptions or fossil fuels and notes metal production can form SO2, indicating multiple large non‑transport sources.

Use this to suspect that industrial processes and power generation (fossil fuel combustion) are important SO2 sources that may exceed locomotive emissions.

Remedial measures emphasise curtailing emissions from thermal and other chemical plants and using low‑sulfur coal, implying thermal power and industry are priority SO2 sources.

A student could infer that if policy targets thermal/industrial sources, those sectors likely contribute more SO2 than individual transport modes like locomotives.

Notes diesel locomotives were introduced and caused environmental pollution, later shifted to electric traction to reduce pollution—showing locomotives are a known source of emissions but not quantifying scale.

Combine this with knowledge of fleet size/fuel use to estimate locomotive SO2 emissions and compare with larger stationary sources to assess relative rankings.