The correct answer is: B. Sulphur
Sulphur is the only nonmetal that shows allotropy in the liquid state. Allotropy is the property of some chemical elements to exist in two or more different forms, called allotropes, with different physical properties. Sulphur has two common allotropes: rhombic sulphur and monoclinic sulphur. Rhombic sulphur is the most stable form of sulphur and is found in nature. It is a yellow, crystalline solid that melts at 119 °C. Monoclinic sulphur is less stable than rhombic sulphur and is formed when rhombic sulphur is heated to 119 °C and then cooled slowly. It is a white, needle-like solid that melts at 120 °C.
Carbon, phosphorus, and bromine do not show allotropy in the liquid state. Carbon exists in two main allotropes: graphite and diamond. Graphite is a soft, black solid that is used in pencils and lubricants. Diamond is a hard, colorless solid that is used in jewelry and cutting tools. Phosphorus exists in three main allotropes: white phosphorus, red phosphorus, and black phosphorus. White phosphorus is a waxy, white solid that is highly flammable. Red phosphorus is a red, amorphous solid that is less flammable than white phosphorus. Black phosphorus is a black, crystalline solid that is the most stable form of phosphorus. Bromine is a red-brown liquid that is the only nonmetal that is liquid at room temperature.
In conclusion, the only nonmetal that shows allotropy in the liquid state is sulphur.