Which of the following metals can readily react with water?

Potassium is a highly reactive metal and reacts readily with water, forming potassium hydroxide and hydrogen gas: 2K + 2H2O → 2KOH + H2↑. Zinc does not react with cold water; it reacts with steam to form zinc oxide and hydrogen. Aluminium generally does not react with water because its surface is protected by a thin layer of aluminium oxide, though it can react with steam. Lead also does not react with water. Therefore, among the given metals, potassium shows the most immediate reaction with water and is the correct option.