Explanation:
Period of a spring mass arrangement is given by
          [tex]T=2\pi\sqrt{\frac{m}{k}}[/tex]
    where m is mass and k is spring constant.
So period of spring mass arrangement is independent of amplitude of motion.
Here amplitude changes from A to 2A.
Period for amplitude A is given by T.
Since period remains same for amplitude 2A also, the period is T.
Option B is the correct answer.