Which of the following sources provides both calcium and sulfur to plants?

Gypsum is a mineral composed primarily of calcium sulfate (CaSO4), which means it provides both calcium and sulfur to plants. Calcium is essential for plant structural integrity and plays a critical role in various physiological processes, including cell wall formation and cell division. Sulfur is also an important nutrient, as it is a key component of amino acids and proteins, as well as coenzymes that aid in various metabolic functions.

In contrast, elemental sulfur offers only sulfur and does not supply any calcium. Magnesium oxide is primarily a source of magnesium, lacking both calcium and sulfur. Muriate of potash mainly provides potassium chloride, which does not contribute calcium or sulfur. Thus, gypsum stands out as the correct source that supplies both of these essential nutrients for plant growth.