I have a duracell deep cycle batery but my charger asks if it is a standard,gel or a a.g.m., what kind is it?

If you bought a regular Deep Cycle Battery, then you have a "Standard" wet cell battery. You would know if you bought a "Gel Cell" or AGM battery. They cost a lot more money and the casing would also be marked Gell Cell or Absorbed Glass Mat battery.