Answer
D..The enzyme changes shape and can no longer speed up the reaction.
Step-by-step explanation:
We are a graph which shows the activity of an enzyme changes at different temperatures.
We have to find that which statement describe what happens to the reaction increases to 63 degrees.
We know that enzymes are biological catalyst and made from proteins .
It does not change in the reaction.
Catalyst increase the rate of reaction but do not any change in the reaction.
Therefore , when temperature increase then rate of reaction increases upto optimized level and then decreases when temperature increases.
Hence,option D is true.