Explanation:

- Supply only: This option suggests equilibrium price is set solely by supply, which isn't true. Supply alone can't determine price without considering demand.

- The Government: Governments can influence prices, but the equilibrium price is usually determined naturally by market forces, not solely by government actions.

- Demand only: This option indicates that only demand influences the equilibrium price, which is incorrect. Demand must interact with supply.

- Demand and supply: This option is correct. The equilibrium price is where demand and supply meet, balancing the quantity consumers want with the quantity producers offer.