Enzymes are biological catalysts. Catalysts lower the activation energy for reactions. The lower the activation energy for a reaction, the faster the rate. Thus enzymes speed up reactions by lowering activation energy.
The lac repressor prevents the lac genes in the DNA of E. coli from being expressed most of the time. The answer to your question is A. I hope this is the answer that you are looking for and it comes to your help.
Tissues are composed of the same kind of cell
