Pls help, I have a test on this, with explanation.

the answer is B

Explanation:

we assume that all of these springs have tha same k , the spring constant

elastic energy for the initial system = Ep1=  

for the new changed system , the spring constant = k1+k2 = k+k = 2k  , but the displacement is also reduced to 0.5 d

so Ep2 =

so the new total Ep stored in the new system is 1/2Ep

hope it helps