Suhita took out 100cm3 of X molar aqueous solution of hydrogen peroxide from the refrigerator. On warming to 19.5ºC, she observed 3dm3 of oxygen gas was produced (at 1 atm pressure). Assuming complete decomposition of hydrogen peroxide, the value of X is approximately (A) 1.25 (B) 2.5 (C) 0.8 (D) 0.5