What is the difference between sweet and sour crude oil?

The distinction between sweet and sour crude oil fundamentally revolves around their sulfur content. Sweet crude oil is characterized by having low sulfur content, typically less than 0.5% by weight. This lower sulfur concentration makes sweet crude desirable due to its reduced environmental impact during combustion and its easier processing in refineries. In contrast, sour crude contains a higher sulfur content, which requires additional processing to remove the sulfur compounds. This extra step can complicate refining and increase costs, making sour crude less favorable compared to sweet crude.

The sulfur levels influence not only the market value of the crude oil but also the refining processes required to make the crude usable as fuel. As such, option B correctly identifies sweet crude's low sulfur content and sour crude's high sulfur content, reflecting the essential difference in their chemical composition and resulting implications for refining and environmental considerations.