According to the graph, what condition is best for enzyme

This increases the chances of a successful collision and so the rate increases. There is a certain temperature at which an enzyme's catalytic activity is at its greatest (see graph). This optimal temperature is usually around human body temperature (37.5 oC) for the enzymes in human cells.

The optimal temperature is usually around human body temperature (37.5 oC) for the enzymes in human cells to work effectively.