D

Step 1: Identify the binding energies of the elements involved in each reaction.
From the question, let’s denote the elements accordingly:
A: mass number = 30, binding energy = 5 MeV
B: mass number = 60, binding energy = 8.5 MeV
C: mass number = 90, binding energy = 7 MeV
D: mass number = 120, binding energy = 8 MeV.

Step 2: Analyze each reaction for energy release:
(1) D → 2B: The mass-energy before the reaction is the binding energy of D. The mass-energy after the reaction is the sum of the binding energies of 2B. Thus, energy is released since 2(8.5) < 8.
(2) C → B + A: Energy is released here as well because the binding energy of B + A is less than C.
(3) B → 2A: This process also releases energy since the binding energy of 2A is less than B.

Step 3: Therefore, energy is released in all three reactions. Thus, the correct answer is D.