i think that this wuestion may have more than 1 answer!!

we should look into references to make sure that one of them is right

i think that(1) is right because this envolves oxygen
but i am not totally sure

if someone knows the answer and sure of it then plz contact me cuz i need that very much

i wish u luck with your exams

For Highly Exothermic may mean that the reaction between the two elements would be very reactive and high amount of energy would be released.

For option C, Flourine is the most reactive halide element as it is at the top of group VII while potassium is the most reactive in the Reactivity Series, so that leads me to conclude that by reacting two highly reactive elements together, the amount of energy that is being produced would be a lot.

Option B is definitely out in my opinion for reacting elements with a noble gas would not produce high amount of energy, if not, no reaction?

Option D would produce less amount of energy as compared to option C, for the metal used is magnesium and magnesium is less reactive than potassium. Sulphur is also less reactive than flourine. Am I correct?

What I am not really sure is option A, for it involved oxygen. If the reaction between oxygen and hydrogen involves combustion, then wouldn’t the amount of energy released be a lot?

Mind correcting me if I am wrong. Thanks alot anyway:)