Fusion reaction takes place at high temperature because:
Molecules break up at high temperature
Nuclei break up at high temperature
Atoms get ionized at high temperature
Kinetic energy is high enough to overcome the coulomb repulsion between nuclei
Option 1)
Molecules break up at high temperature
Option 2)
Nuclei break up at high temperature
Option 3)
Atoms get ionized at high temperature
Option 4)
Kinetic energy is high enough to overcome the coulomb repulsion between nuclei