Alkali metals react with water to form bases and release hydrogen gas because:

• A
  Their position in the electrochemical series,based on oxidation potential,is much higher than hydrogen.
• B
  Their position in the electrochemical series,based on oxidation potential,is much lower than hydrogen.
• C
  Their ionization potential is much lower than other elements.
• D
  They possess only one electron in their outermost shell.