I believe option B would be the correct choice because, without a catalyst, the reaction will be either too slow or will not happen at all as it would not acquire a fitting activation energy for the reaction.Β
If you would like to know why the other options are incorrect, please read on:Β
Option A is incorrect because since proteins are specific in nature, so other protein cannot be replaced, for some other chemical reaction.Β
Option C is not correct it is a genetic defect that the protein does not form, and all cells are genetically identical, a reaction cannot take place in any parts of the body.Β
And finally, option D would be wrong because if a forward reaction does not take place, a backwards reaction will not occur.Β
I hope this answer has helped, and I apologise if somehow this answer finds itself to be incorrect. Good luck on your quiz or homework. :)Β