Why is the deuterium-tritium reaction the most promising nuclear fusion reaction for future energy production?

The most promising of the nuclear fusions reactions for the future is the deuterium-tritium fusion, it comprises the deuterium cycle in which an amalgamation of tritium and deuterium takes place. The reaction produces an enormous energy of 17.6 MeV, however, to attain fusion there is a need to infiltrate the coulomb barrier with the help of tunneling, needing very high temperatures.  

the correct answer is a

what's the