Which of the following represents the chemical symbol for strontium?

The chemical symbol for strontium is represented by the letters "Sr." Each element in the periodic table has a unique one- or two-letter symbol derived from its name, often reflecting its Latin or Greek roots. Strontium's name is derived from the mineral strontianite, which gets its name from the Scottish village of Strontian. The letters "Sr" are both an abbreviation of the element's name and are distinctive to avoid confusion with other elements.

The other options do not correlate with the elemental symbol for strontium; "St" does not correspond to any element, "Sm" is the symbol for samarium, and "S" represents sulfur. Therefore, "Sr" is the only accurate representation for strontium among the choices provided.