Which one of the following nonmetals shows allotropy in the liquid state?

Sulphur is a non-metal that shows allotropy in the liquid state. If sulphur is heated slowly the changes between the different forms can be observed. These changes are in the form of colour and viscosity (thickness) of the liquid. If the dark brown liquid sulphur is poured into a beaker of cold water, plastic sulphur is formed. This is an elastic, rubber-like form of sulphur.