In a theoretical world where all things are possible, how could you increase the amount of energy that could be stored in a molecule of atp?

this can be done by increasing the negative charges of each of the phosphate group bonded  to the ADENOSINE GROUPS

Explanation;

Basically the hydrolysis of ATP generate large amount of energy of 30.5kj from each phosphate bond broken for ATP usage. However the amount   energy liberated depends on the strong  negative charges  of repulsion  of phosphate ions bonded to each Adenosine group.

Consequently, anything that increases the number  charges  for repulsion should increase the ENERGY LIBERATED DURING HYDROLYSIS OF ATP TO

ADP +Pi

and

ADP → AMP +Pi

the answer would be d

answer; both surfaces of the membrane are nonpermeable