Some proteins catalyze biochemical reactions. if a genetic defect prevented a protein catalyst from being produced which of the following would happen in a cell?
a. the cell would find a different type of protein to catalyze the reaction.
b. the reaction the protein catalyzes would proceed very slowly or not at all.
c. the reaction the protein catalyzes would only occur in some places in the cell.
d. the reverse reaction of the one the protein catalyzes would begin to proceed.

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. 
If you would like to know why the other options are incorrect, please read on: 
Option A is incorrect because since proteins are specific in nature, so other protein cannot be replaced, for some other chemical reaction. 
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. 
And finally, option D would be wrong because if a forward reaction does not take place, a backwards reaction will not occur. 
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. :)