The answer is 100%
let me know if you want an explanation
Conduction - by touch
Convection - hot air rises, cold air sinks
Insulation - to insulate or capture heat
Radiation - by waves
Direct contact means touch, therefore the answer would be conduction.
The heat released/absorbed by a reaction that occurs at constant pressure.
Hope this helped :)
Explanation:
By ordinary chemical means/reaction
